[GitHub] [nifi] gresockj commented on a change in pull request #5460: NIFI-9304 - Adding PublishGCPubSubLite and ConsumeGCPubSubLite processors

[GitBox]

gresockj commented on a change in pull request #5460:
URL: https://github.com/apache/nifi/pull/5460#discussion_r737325551



##########
File path: nifi-nar-bundles/nifi-gcp-bundle/nifi-gcp-processors/pom.xml
##########
@@ -89,6 +89,15 @@
             <groupId>com.google.cloud</groupId>
             <artifactId>google-cloud-pubsub</artifactId>
         </dependency>
+        <dependency>

Review comment:
       Looks like this is a duplicate from the dependency just above it

##########
File path: 
nifi-nar-bundles/nifi-gcp-bundle/nifi-gcp-processors/src/main/java/org/apache/nifi/processors/gcp/pubsub/lite/ConsumeGCPubSubLite.java
##########
@@ -0,0 +1,258 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.processors.gcp.pubsub.lite;
+
+import com.google.api.gax.core.FixedCredentialsProvider;
+import com.google.api.gax.rpc.ApiException;
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.cloud.pubsub.v1.MessageReceiver;
+import com.google.cloud.pubsublite.SubscriptionPath;
+import com.google.cloud.pubsublite.cloudpubsub.FlowControlSettings;
+import com.google.cloud.pubsublite.cloudpubsub.Subscriber;
+import com.google.cloud.pubsublite.cloudpubsub.SubscriberSettings;
+import com.google.common.collect.ImmutableList;
+import com.google.pubsub.v1.PubsubMessage;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.SeeAlso;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.annotation.lifecycle.OnStopped;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.DataUnit;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.processors.gcp.pubsub.AbstractGCPubSubProcessor;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_DESCRIPTION;
+
+@SeeAlso({PublishGCPubSubLite.class})
+@InputRequirement(InputRequirement.Requirement.INPUT_FORBIDDEN)
+@Tags({"google", "google-cloud", "gcp", "message", "pubsub", "consume", 
"lite"})
+@CapabilityDescription("Consumes message from the configured Google Cloud 
PubSub Lite subscription.")
+@WritesAttributes({
+        @WritesAttribute(attribute = MESSAGE_ID_ATTRIBUTE, description = 
MESSAGE_ID_DESCRIPTION),
+        @WritesAttribute(attribute = ORDERING_KEY_ATTRIBUTE, description = 
ORDERING_KEY_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_ATTRIBUTES_COUNT_ATTRIBUTE, 
description = MSG_ATTRIBUTES_COUNT_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_PUBLISH_TIME_ATTRIBUTE, description = 
MSG_PUBLISH_TIME_DESCRIPTION),
+        @WritesAttribute(attribute = DYNAMIC_ATTRIBUTES_ATTRIBUTE, description 
= DYNAMIC_ATTRIBUTES_DESCRIPTION)
+})
+public class ConsumeGCPubSubLite extends AbstractGCPubSubProcessor {
+
+    public static final PropertyDescriptor SUBSCRIPTION = new 
PropertyDescriptor.Builder()
+            .name("gcp-pubsub-subscription")
+            .displayName("Subscription")
+            .addValidator(StandardValidators.NON_EMPTY_EL_VALIDATOR)
+            .description("Name of the Google Cloud Pub/Sub Subscription. 
Example: 
projects/8476107443/locations/europe-west1-d/subscriptions/my-lite-subscription")
+            .required(true)
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .build();
+
+    public static final PropertyDescriptor BYTES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-bytes-outstanding")
+            .displayName("Bytes Outstanding")
+            .description("The number of quota bytes that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("10 MB")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.DATA_SIZE_VALIDATOR)
+            .build();
+
+    public static final PropertyDescriptor MESSAGES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-messages-outstanding")
+            .displayName("Messages Outstanding")
+            .description("The number of messages that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("1000")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.POSITIVE_INTEGER_VALIDATOR)
+            .build();
+
+    private Subscriber subscriber = null;
+    private static final BlockingQueue<Message> messages = new 
LinkedBlockingQueue<>();
+
+    @Override
+    protected Collection<ValidationResult> customValidate(ValidationContext 
validationContext) {
+        final Collection<ValidationResult> results = new 
ArrayList<ValidationResult>(1);
+        final String subscription = 
validationContext.getProperty(SUBSCRIPTION).evaluateAttributeExpressions().getValue();
+
+        try {
+            SubscriptionPath.parse(subscription);
+        } catch (ApiException e) {
+            results.add(new ValidationResult.Builder()
+                    .subject(SUBSCRIPTION.getName())
+                    .input(subscription)
+                    .valid(false)
+                    .explanation("The Suscription does not have a valid 
format.")
+                    .build());
+        }
+
+        return results;
+    }
+
+    @OnScheduled
+    public void onScheduled(ProcessContext context) {
+        try {
+            subscriber = getSubscriber(context);
+        } catch (Exception e) {
+            getLogger().error("Failed to create Google Cloud Subscriber", e);
+            throw new ProcessException(e);
+        }
+        try {
+            subscriber.startAsync().awaitRunning();
+        } catch (Exception e) {
+            getLogger().error("Failed to create Google Cloud Subscriber", 
subscriber.failureCause());
+            throw new ProcessException(e);
+        }
+    }
+
+    @OnStopped
+    public void onStopped() {
+        try {
+            if (subscriber != null) {
+                subscriber.stopAsync().awaitTerminated();
+            }
+        } catch (Exception e) {

Review comment:
       Exception could be `final` here

##########
File path: 
nifi-nar-bundles/nifi-gcp-bundle/nifi-gcp-processors/src/main/java/org/apache/nifi/processors/gcp/pubsub/lite/ConsumeGCPubSubLite.java
##########
@@ -0,0 +1,258 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.processors.gcp.pubsub.lite;
+
+import com.google.api.gax.core.FixedCredentialsProvider;
+import com.google.api.gax.rpc.ApiException;
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.cloud.pubsub.v1.MessageReceiver;
+import com.google.cloud.pubsublite.SubscriptionPath;
+import com.google.cloud.pubsublite.cloudpubsub.FlowControlSettings;
+import com.google.cloud.pubsublite.cloudpubsub.Subscriber;
+import com.google.cloud.pubsublite.cloudpubsub.SubscriberSettings;
+import com.google.common.collect.ImmutableList;
+import com.google.pubsub.v1.PubsubMessage;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.SeeAlso;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.annotation.lifecycle.OnStopped;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.DataUnit;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.processors.gcp.pubsub.AbstractGCPubSubProcessor;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_DESCRIPTION;
+
+@SeeAlso({PublishGCPubSubLite.class})
+@InputRequirement(InputRequirement.Requirement.INPUT_FORBIDDEN)
+@Tags({"google", "google-cloud", "gcp", "message", "pubsub", "consume", 
"lite"})
+@CapabilityDescription("Consumes message from the configured Google Cloud 
PubSub Lite subscription.")
+@WritesAttributes({
+        @WritesAttribute(attribute = MESSAGE_ID_ATTRIBUTE, description = 
MESSAGE_ID_DESCRIPTION),
+        @WritesAttribute(attribute = ORDERING_KEY_ATTRIBUTE, description = 
ORDERING_KEY_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_ATTRIBUTES_COUNT_ATTRIBUTE, 
description = MSG_ATTRIBUTES_COUNT_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_PUBLISH_TIME_ATTRIBUTE, description = 
MSG_PUBLISH_TIME_DESCRIPTION),
+        @WritesAttribute(attribute = DYNAMIC_ATTRIBUTES_ATTRIBUTE, description 
= DYNAMIC_ATTRIBUTES_DESCRIPTION)
+})
+public class ConsumeGCPubSubLite extends AbstractGCPubSubProcessor {
+
+    public static final PropertyDescriptor SUBSCRIPTION = new 
PropertyDescriptor.Builder()
+            .name("gcp-pubsub-subscription")
+            .displayName("Subscription")
+            .addValidator(StandardValidators.NON_EMPTY_EL_VALIDATOR)
+            .description("Name of the Google Cloud Pub/Sub Subscription. 
Example: 
projects/8476107443/locations/europe-west1-d/subscriptions/my-lite-subscription")
+            .required(true)
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .build();
+
+    public static final PropertyDescriptor BYTES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-bytes-outstanding")
+            .displayName("Bytes Outstanding")
+            .description("The number of quota bytes that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("10 MB")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.DATA_SIZE_VALIDATOR)
+            .build();
+
+    public static final PropertyDescriptor MESSAGES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-messages-outstanding")
+            .displayName("Messages Outstanding")
+            .description("The number of messages that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("1000")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.POSITIVE_INTEGER_VALIDATOR)
+            .build();
+
+    private Subscriber subscriber = null;
+    private static final BlockingQueue<Message> messages = new 
LinkedBlockingQueue<>();
+
+    @Override
+    protected Collection<ValidationResult> customValidate(ValidationContext 
validationContext) {
+        final Collection<ValidationResult> results = new 
ArrayList<ValidationResult>(1);
+        final String subscription = 
validationContext.getProperty(SUBSCRIPTION).evaluateAttributeExpressions().getValue();
+
+        try {
+            SubscriptionPath.parse(subscription);
+        } catch (ApiException e) {
+            results.add(new ValidationResult.Builder()
+                    .subject(SUBSCRIPTION.getName())
+                    .input(subscription)
+                    .valid(false)
+                    .explanation("The Suscription does not have a valid 
format.")
+                    .build());
+        }
+
+        return results;
+    }
+
+    @OnScheduled
+    public void onScheduled(ProcessContext context) {
+        try {
+            subscriber = getSubscriber(context);
+        } catch (Exception e) {

Review comment:
       Exception could be `final` here

##########
File path: 
nifi-nar-bundles/nifi-gcp-bundle/nifi-gcp-processors/src/main/java/org/apache/nifi/processors/gcp/pubsub/lite/ConsumeGCPubSubLite.java
##########
@@ -0,0 +1,258 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.processors.gcp.pubsub.lite;
+
+import com.google.api.gax.core.FixedCredentialsProvider;
+import com.google.api.gax.rpc.ApiException;
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.cloud.pubsub.v1.MessageReceiver;
+import com.google.cloud.pubsublite.SubscriptionPath;
+import com.google.cloud.pubsublite.cloudpubsub.FlowControlSettings;
+import com.google.cloud.pubsublite.cloudpubsub.Subscriber;
+import com.google.cloud.pubsublite.cloudpubsub.SubscriberSettings;
+import com.google.common.collect.ImmutableList;
+import com.google.pubsub.v1.PubsubMessage;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.SeeAlso;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.annotation.lifecycle.OnStopped;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.DataUnit;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.processors.gcp.pubsub.AbstractGCPubSubProcessor;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_DESCRIPTION;
+
+@SeeAlso({PublishGCPubSubLite.class})
+@InputRequirement(InputRequirement.Requirement.INPUT_FORBIDDEN)
+@Tags({"google", "google-cloud", "gcp", "message", "pubsub", "consume", 
"lite"})
+@CapabilityDescription("Consumes message from the configured Google Cloud 
PubSub Lite subscription.")
+@WritesAttributes({
+        @WritesAttribute(attribute = MESSAGE_ID_ATTRIBUTE, description = 
MESSAGE_ID_DESCRIPTION),
+        @WritesAttribute(attribute = ORDERING_KEY_ATTRIBUTE, description = 
ORDERING_KEY_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_ATTRIBUTES_COUNT_ATTRIBUTE, 
description = MSG_ATTRIBUTES_COUNT_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_PUBLISH_TIME_ATTRIBUTE, description = 
MSG_PUBLISH_TIME_DESCRIPTION),
+        @WritesAttribute(attribute = DYNAMIC_ATTRIBUTES_ATTRIBUTE, description 
= DYNAMIC_ATTRIBUTES_DESCRIPTION)
+})
+public class ConsumeGCPubSubLite extends AbstractGCPubSubProcessor {
+
+    public static final PropertyDescriptor SUBSCRIPTION = new 
PropertyDescriptor.Builder()
+            .name("gcp-pubsub-subscription")
+            .displayName("Subscription")
+            .addValidator(StandardValidators.NON_EMPTY_EL_VALIDATOR)
+            .description("Name of the Google Cloud Pub/Sub Subscription. 
Example: 
projects/8476107443/locations/europe-west1-d/subscriptions/my-lite-subscription")
+            .required(true)
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .build();
+
+    public static final PropertyDescriptor BYTES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-bytes-outstanding")
+            .displayName("Bytes Outstanding")
+            .description("The number of quota bytes that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("10 MB")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.DATA_SIZE_VALIDATOR)
+            .build();
+
+    public static final PropertyDescriptor MESSAGES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-messages-outstanding")
+            .displayName("Messages Outstanding")
+            .description("The number of messages that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("1000")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.POSITIVE_INTEGER_VALIDATOR)
+            .build();
+
+    private Subscriber subscriber = null;
+    private static final BlockingQueue<Message> messages = new 
LinkedBlockingQueue<>();
+
+    @Override
+    protected Collection<ValidationResult> customValidate(ValidationContext 
validationContext) {
+        final Collection<ValidationResult> results = new 
ArrayList<ValidationResult>(1);
+        final String subscription = 
validationContext.getProperty(SUBSCRIPTION).evaluateAttributeExpressions().getValue();
+
+        try {
+            SubscriptionPath.parse(subscription);
+        } catch (ApiException e) {
+            results.add(new ValidationResult.Builder()
+                    .subject(SUBSCRIPTION.getName())
+                    .input(subscription)
+                    .valid(false)
+                    .explanation("The Suscription does not have a valid 
format.")
+                    .build());
+        }
+
+        return results;
+    }
+
+    @OnScheduled
+    public void onScheduled(ProcessContext context) {
+        try {
+            subscriber = getSubscriber(context);
+        } catch (Exception e) {
+            getLogger().error("Failed to create Google Cloud Subscriber", e);
+            throw new ProcessException(e);
+        }
+        try {
+            subscriber.startAsync().awaitRunning();
+        } catch (Exception e) {
+            getLogger().error("Failed to create Google Cloud Subscriber", 
subscriber.failureCause());
+            throw new ProcessException(e);
+        }
+    }
+
+    @OnStopped
+    public void onStopped() {
+        try {
+            if (subscriber != null) {
+                subscriber.stopAsync().awaitTerminated();
+            }
+        } catch (Exception e) {
+            getLogger().warn("Failed to gracefully shutdown the Google Cloud 
PubSub Lite Subscriber", e);
+        }
+    }
+
+    @Override
+    public List<PropertyDescriptor> getSupportedPropertyDescriptors() {
+        return ImmutableList.of(SUBSCRIPTION,
+                GCP_CREDENTIALS_PROVIDER_SERVICE,
+                BYTES_OUTSTANDING,
+                MESSAGES_OUTSTANDING);
+    }
+
+    @Override
+    public Set<Relationship> getRelationships() {
+        return Collections.singleton(REL_SUCCESS);
+    }
+
+    @Override
+    public void onTrigger(final ProcessContext context, final ProcessSession 
session) throws ProcessException {
+        if (subscriber == null) {
+            getLogger().error("Google Cloud PubSub Subscriber was not properly 
created. Yielding the processor...");
+            context.yield();
+            return;
+        }
+
+        if(!subscriber.isRunning()) {
+            getLogger().error("Google Cloud PubSub Subscriber is not running. 
Yielding the processor...", subscriber.failureCause());
+            throw new ProcessException(subscriber.failureCause());
+        }
+
+        Message message = messages.poll();
+        if(message == null) {
+            context.yield();
+            return;
+        }
+
+        FlowFile flowFile = session.create();
+
+        final Map<String, String> attributes = new HashMap<>();
+        attributes.put(MESSAGE_ID_ATTRIBUTE, 
message.getMessage().getMessageId());
+        attributes.put(ORDERING_KEY_ATTRIBUTE, 
message.getMessage().getOrderingKey());
+        attributes.put(MSG_ATTRIBUTES_COUNT_ATTRIBUTE, 
String.valueOf(message.getMessage().getAttributesCount()));
+        attributes.put(MSG_PUBLISH_TIME_ATTRIBUTE, 
String.valueOf(message.getMessage().getPublishTime().getSeconds()));
+        attributes.putAll(message.getMessage().getAttributesMap());
+
+        flowFile = session.putAllAttributes(flowFile, attributes);
+        flowFile = session.write(flowFile, out -> 
out.write(message.getMessage().getData().toStringUtf8().getBytes()));
+
+        session.transfer(flowFile, REL_SUCCESS);
+        session.getProvenanceReporter().receive(flowFile, 
context.getProperty(SUBSCRIPTION).evaluateAttributeExpressions().getValue());
+
+        message.getConsumer().ack();
+    }
+
+    private Subscriber getSubscriber(final ProcessContext context) throws 
IOException {
+
+        SubscriptionPath subscriptionPath = 
SubscriptionPath.parse(context.getProperty(SUBSCRIPTION).evaluateAttributeExpressions().getValue());

Review comment:
       These local variables could all be `final`

##########
File path: 
nifi-nar-bundles/nifi-gcp-bundle/nifi-gcp-processors/src/main/java/org/apache/nifi/processors/gcp/pubsub/lite/ConsumeGCPubSubLite.java
##########
@@ -0,0 +1,258 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.processors.gcp.pubsub.lite;
+
+import com.google.api.gax.core.FixedCredentialsProvider;
+import com.google.api.gax.rpc.ApiException;
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.cloud.pubsub.v1.MessageReceiver;
+import com.google.cloud.pubsublite.SubscriptionPath;
+import com.google.cloud.pubsublite.cloudpubsub.FlowControlSettings;
+import com.google.cloud.pubsublite.cloudpubsub.Subscriber;
+import com.google.cloud.pubsublite.cloudpubsub.SubscriberSettings;
+import com.google.common.collect.ImmutableList;
+import com.google.pubsub.v1.PubsubMessage;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.SeeAlso;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.annotation.lifecycle.OnStopped;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.DataUnit;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.processors.gcp.pubsub.AbstractGCPubSubProcessor;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_DESCRIPTION;
+
+@SeeAlso({PublishGCPubSubLite.class})
+@InputRequirement(InputRequirement.Requirement.INPUT_FORBIDDEN)
+@Tags({"google", "google-cloud", "gcp", "message", "pubsub", "consume", 
"lite"})
+@CapabilityDescription("Consumes message from the configured Google Cloud 
PubSub Lite subscription.")
+@WritesAttributes({
+        @WritesAttribute(attribute = MESSAGE_ID_ATTRIBUTE, description = 
MESSAGE_ID_DESCRIPTION),
+        @WritesAttribute(attribute = ORDERING_KEY_ATTRIBUTE, description = 
ORDERING_KEY_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_ATTRIBUTES_COUNT_ATTRIBUTE, 
description = MSG_ATTRIBUTES_COUNT_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_PUBLISH_TIME_ATTRIBUTE, description = 
MSG_PUBLISH_TIME_DESCRIPTION),
+        @WritesAttribute(attribute = DYNAMIC_ATTRIBUTES_ATTRIBUTE, description 
= DYNAMIC_ATTRIBUTES_DESCRIPTION)
+})
+public class ConsumeGCPubSubLite extends AbstractGCPubSubProcessor {
+
+    public static final PropertyDescriptor SUBSCRIPTION = new 
PropertyDescriptor.Builder()
+            .name("gcp-pubsub-subscription")
+            .displayName("Subscription")
+            .addValidator(StandardValidators.NON_EMPTY_EL_VALIDATOR)
+            .description("Name of the Google Cloud Pub/Sub Subscription. 
Example: 
projects/8476107443/locations/europe-west1-d/subscriptions/my-lite-subscription")
+            .required(true)
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .build();
+
+    public static final PropertyDescriptor BYTES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-bytes-outstanding")
+            .displayName("Bytes Outstanding")
+            .description("The number of quota bytes that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("10 MB")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.DATA_SIZE_VALIDATOR)
+            .build();
+
+    public static final PropertyDescriptor MESSAGES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-messages-outstanding")
+            .displayName("Messages Outstanding")
+            .description("The number of messages that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("1000")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.POSITIVE_INTEGER_VALIDATOR)
+            .build();
+
+    private Subscriber subscriber = null;
+    private static final BlockingQueue<Message> messages = new 
LinkedBlockingQueue<>();
+
+    @Override
+    protected Collection<ValidationResult> customValidate(ValidationContext 
validationContext) {
+        final Collection<ValidationResult> results = new 
ArrayList<ValidationResult>(1);
+        final String subscription = 
validationContext.getProperty(SUBSCRIPTION).evaluateAttributeExpressions().getValue();
+
+        try {
+            SubscriptionPath.parse(subscription);
+        } catch (ApiException e) {
+            results.add(new ValidationResult.Builder()
+                    .subject(SUBSCRIPTION.getName())
+                    .input(subscription)
+                    .valid(false)
+                    .explanation("The Suscription does not have a valid 
format.")
+                    .build());
+        }
+
+        return results;
+    }
+
+    @OnScheduled
+    public void onScheduled(ProcessContext context) {
+        try {
+            subscriber = getSubscriber(context);
+        } catch (Exception e) {
+            getLogger().error("Failed to create Google Cloud Subscriber", e);
+            throw new ProcessException(e);
+        }
+        try {
+            subscriber.startAsync().awaitRunning();
+        } catch (Exception e) {
+            getLogger().error("Failed to create Google Cloud Subscriber", 
subscriber.failureCause());
+            throw new ProcessException(e);
+        }
+    }
+
+    @OnStopped
+    public void onStopped() {
+        try {
+            if (subscriber != null) {
+                subscriber.stopAsync().awaitTerminated();
+            }
+        } catch (Exception e) {
+            getLogger().warn("Failed to gracefully shutdown the Google Cloud 
PubSub Lite Subscriber", e);
+        }
+    }
+
+    @Override
+    public List<PropertyDescriptor> getSupportedPropertyDescriptors() {
+        return ImmutableList.of(SUBSCRIPTION,
+                GCP_CREDENTIALS_PROVIDER_SERVICE,
+                BYTES_OUTSTANDING,
+                MESSAGES_OUTSTANDING);
+    }
+
+    @Override
+    public Set<Relationship> getRelationships() {
+        return Collections.singleton(REL_SUCCESS);
+    }
+
+    @Override
+    public void onTrigger(final ProcessContext context, final ProcessSession 
session) throws ProcessException {
+        if (subscriber == null) {
+            getLogger().error("Google Cloud PubSub Subscriber was not properly 
created. Yielding the processor...");
+            context.yield();
+            return;
+        }
+
+        if(!subscriber.isRunning()) {
+            getLogger().error("Google Cloud PubSub Subscriber is not running. 
Yielding the processor...", subscriber.failureCause());
+            throw new ProcessException(subscriber.failureCause());
+        }
+
+        Message message = messages.poll();
+        if(message == null) {
+            context.yield();
+            return;
+        }
+
+        FlowFile flowFile = session.create();
+
+        final Map<String, String> attributes = new HashMap<>();
+        attributes.put(MESSAGE_ID_ATTRIBUTE, 
message.getMessage().getMessageId());
+        attributes.put(ORDERING_KEY_ATTRIBUTE, 
message.getMessage().getOrderingKey());
+        attributes.put(MSG_ATTRIBUTES_COUNT_ATTRIBUTE, 
String.valueOf(message.getMessage().getAttributesCount()));
+        attributes.put(MSG_PUBLISH_TIME_ATTRIBUTE, 
String.valueOf(message.getMessage().getPublishTime().getSeconds()));
+        attributes.putAll(message.getMessage().getAttributesMap());
+
+        flowFile = session.putAllAttributes(flowFile, attributes);
+        flowFile = session.write(flowFile, out -> 
out.write(message.getMessage().getData().toStringUtf8().getBytes()));
+
+        session.transfer(flowFile, REL_SUCCESS);
+        session.getProvenanceReporter().receive(flowFile, 
context.getProperty(SUBSCRIPTION).evaluateAttributeExpressions().getValue());
+
+        message.getConsumer().ack();
+    }
+
+    private Subscriber getSubscriber(final ProcessContext context) throws 
IOException {
+
+        SubscriptionPath subscriptionPath = 
SubscriptionPath.parse(context.getProperty(SUBSCRIPTION).evaluateAttributeExpressions().getValue());
+
+        FlowControlSettings flowControlSettings = FlowControlSettings.builder()
+                
.setBytesOutstanding(context.getProperty(BYTES_OUTSTANDING).evaluateAttributeExpressions().asDataSize(DataUnit.B).longValue())
+                
.setMessagesOutstanding(context.getProperty(MESSAGES_OUTSTANDING).evaluateAttributeExpressions().asLong())
+                .build();
+
+        MessageReceiver receiver =
+                (PubsubMessage message, AckReplyConsumer consumer) -> {
+                    try {
+                        messages.put(new Message(message, consumer));
+                    } catch (InterruptedException e) {
+                        getLogger().error("Could not save the message inside 
the internal queue of the processor", e);
+                    }
+                };
+
+        SubscriberSettings subscriberSettings = SubscriberSettings.newBuilder()
+                
.setCredentialsProvider(FixedCredentialsProvider.create(getGoogleCredentials(context)))
+                .setSubscriptionPath(subscriptionPath)
+                .setReceiver(receiver)
+                .setPerPartitionFlowControlSettings(flowControlSettings)
+                .build();
+
+        return Subscriber.create(subscriberSettings);
+    }
+
+    private class Message {
+        private PubsubMessage message;
+        private AckReplyConsumer consumer;
+
+        public Message(PubsubMessage message, AckReplyConsumer consumer) {

Review comment:
       `final` arguments

##########
File path: 
nifi-nar-bundles/nifi-gcp-bundle/nifi-gcp-processors/src/main/java/org/apache/nifi/processors/gcp/pubsub/lite/ConsumeGCPubSubLite.java
##########
@@ -0,0 +1,258 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.processors.gcp.pubsub.lite;
+
+import com.google.api.gax.core.FixedCredentialsProvider;
+import com.google.api.gax.rpc.ApiException;
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.cloud.pubsub.v1.MessageReceiver;
+import com.google.cloud.pubsublite.SubscriptionPath;
+import com.google.cloud.pubsublite.cloudpubsub.FlowControlSettings;
+import com.google.cloud.pubsublite.cloudpubsub.Subscriber;
+import com.google.cloud.pubsublite.cloudpubsub.SubscriberSettings;
+import com.google.common.collect.ImmutableList;
+import com.google.pubsub.v1.PubsubMessage;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.SeeAlso;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.annotation.lifecycle.OnStopped;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.DataUnit;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.processors.gcp.pubsub.AbstractGCPubSubProcessor;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_DESCRIPTION;
+
+@SeeAlso({PublishGCPubSubLite.class})
+@InputRequirement(InputRequirement.Requirement.INPUT_FORBIDDEN)
+@Tags({"google", "google-cloud", "gcp", "message", "pubsub", "consume", 
"lite"})
+@CapabilityDescription("Consumes message from the configured Google Cloud 
PubSub Lite subscription.")

Review comment:
       What do you think about adding a note either here or in 
additionalDetails indicating that Pub/Sub Lite only supports 'Use Application 
Default Credentials' and 'Use Compute Engine Credentials' in the GCP 
Credentials Provider Service?

##########
File path: 
nifi-nar-bundles/nifi-gcp-bundle/nifi-gcp-processors/src/main/java/org/apache/nifi/processors/gcp/pubsub/lite/ConsumeGCPubSubLite.java
##########
@@ -0,0 +1,258 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.processors.gcp.pubsub.lite;
+
+import com.google.api.gax.core.FixedCredentialsProvider;
+import com.google.api.gax.rpc.ApiException;
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.cloud.pubsub.v1.MessageReceiver;
+import com.google.cloud.pubsublite.SubscriptionPath;
+import com.google.cloud.pubsublite.cloudpubsub.FlowControlSettings;
+import com.google.cloud.pubsublite.cloudpubsub.Subscriber;
+import com.google.cloud.pubsublite.cloudpubsub.SubscriberSettings;
+import com.google.common.collect.ImmutableList;
+import com.google.pubsub.v1.PubsubMessage;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.SeeAlso;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.annotation.lifecycle.OnStopped;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.DataUnit;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.processors.gcp.pubsub.AbstractGCPubSubProcessor;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_DESCRIPTION;
+
+@SeeAlso({PublishGCPubSubLite.class})
+@InputRequirement(InputRequirement.Requirement.INPUT_FORBIDDEN)
+@Tags({"google", "google-cloud", "gcp", "message", "pubsub", "consume", 
"lite"})
+@CapabilityDescription("Consumes message from the configured Google Cloud 
PubSub Lite subscription.")
+@WritesAttributes({
+        @WritesAttribute(attribute = MESSAGE_ID_ATTRIBUTE, description = 
MESSAGE_ID_DESCRIPTION),
+        @WritesAttribute(attribute = ORDERING_KEY_ATTRIBUTE, description = 
ORDERING_KEY_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_ATTRIBUTES_COUNT_ATTRIBUTE, 
description = MSG_ATTRIBUTES_COUNT_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_PUBLISH_TIME_ATTRIBUTE, description = 
MSG_PUBLISH_TIME_DESCRIPTION),
+        @WritesAttribute(attribute = DYNAMIC_ATTRIBUTES_ATTRIBUTE, description 
= DYNAMIC_ATTRIBUTES_DESCRIPTION)
+})
+public class ConsumeGCPubSubLite extends AbstractGCPubSubProcessor {
+
+    public static final PropertyDescriptor SUBSCRIPTION = new 
PropertyDescriptor.Builder()
+            .name("gcp-pubsub-subscription")
+            .displayName("Subscription")
+            .addValidator(StandardValidators.NON_EMPTY_EL_VALIDATOR)
+            .description("Name of the Google Cloud Pub/Sub Subscription. 
Example: 
projects/8476107443/locations/europe-west1-d/subscriptions/my-lite-subscription")
+            .required(true)
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .build();
+
+    public static final PropertyDescriptor BYTES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-bytes-outstanding")
+            .displayName("Bytes Outstanding")
+            .description("The number of quota bytes that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("10 MB")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.DATA_SIZE_VALIDATOR)
+            .build();
+
+    public static final PropertyDescriptor MESSAGES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-messages-outstanding")
+            .displayName("Messages Outstanding")
+            .description("The number of messages that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("1000")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.POSITIVE_INTEGER_VALIDATOR)
+            .build();
+
+    private Subscriber subscriber = null;
+    private static final BlockingQueue<Message> messages = new 
LinkedBlockingQueue<>();
+
+    @Override
+    protected Collection<ValidationResult> customValidate(ValidationContext 
validationContext) {

Review comment:
       Consider `final` on the argument here

##########
File path: 
nifi-nar-bundles/nifi-gcp-bundle/nifi-gcp-processors/src/main/java/org/apache/nifi/processors/gcp/pubsub/lite/ConsumeGCPubSubLite.java
##########
@@ -0,0 +1,258 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.processors.gcp.pubsub.lite;
+
+import com.google.api.gax.core.FixedCredentialsProvider;
+import com.google.api.gax.rpc.ApiException;
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.cloud.pubsub.v1.MessageReceiver;
+import com.google.cloud.pubsublite.SubscriptionPath;
+import com.google.cloud.pubsublite.cloudpubsub.FlowControlSettings;
+import com.google.cloud.pubsublite.cloudpubsub.Subscriber;
+import com.google.cloud.pubsublite.cloudpubsub.SubscriberSettings;
+import com.google.common.collect.ImmutableList;
+import com.google.pubsub.v1.PubsubMessage;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.SeeAlso;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.annotation.lifecycle.OnStopped;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.DataUnit;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.processors.gcp.pubsub.AbstractGCPubSubProcessor;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_DESCRIPTION;
+
+@SeeAlso({PublishGCPubSubLite.class})
+@InputRequirement(InputRequirement.Requirement.INPUT_FORBIDDEN)
+@Tags({"google", "google-cloud", "gcp", "message", "pubsub", "consume", 
"lite"})
+@CapabilityDescription("Consumes message from the configured Google Cloud 
PubSub Lite subscription.")
+@WritesAttributes({
+        @WritesAttribute(attribute = MESSAGE_ID_ATTRIBUTE, description = 
MESSAGE_ID_DESCRIPTION),
+        @WritesAttribute(attribute = ORDERING_KEY_ATTRIBUTE, description = 
ORDERING_KEY_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_ATTRIBUTES_COUNT_ATTRIBUTE, 
description = MSG_ATTRIBUTES_COUNT_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_PUBLISH_TIME_ATTRIBUTE, description = 
MSG_PUBLISH_TIME_DESCRIPTION),
+        @WritesAttribute(attribute = DYNAMIC_ATTRIBUTES_ATTRIBUTE, description 
= DYNAMIC_ATTRIBUTES_DESCRIPTION)
+})
+public class ConsumeGCPubSubLite extends AbstractGCPubSubProcessor {
+
+    public static final PropertyDescriptor SUBSCRIPTION = new 
PropertyDescriptor.Builder()
+            .name("gcp-pubsub-subscription")
+            .displayName("Subscription")
+            .addValidator(StandardValidators.NON_EMPTY_EL_VALIDATOR)
+            .description("Name of the Google Cloud Pub/Sub Subscription. 
Example: 
projects/8476107443/locations/europe-west1-d/subscriptions/my-lite-subscription")
+            .required(true)
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .build();
+
+    public static final PropertyDescriptor BYTES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-bytes-outstanding")
+            .displayName("Bytes Outstanding")
+            .description("The number of quota bytes that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("10 MB")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.DATA_SIZE_VALIDATOR)
+            .build();
+
+    public static final PropertyDescriptor MESSAGES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-messages-outstanding")
+            .displayName("Messages Outstanding")
+            .description("The number of messages that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("1000")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.POSITIVE_INTEGER_VALIDATOR)
+            .build();
+
+    private Subscriber subscriber = null;
+    private static final BlockingQueue<Message> messages = new 
LinkedBlockingQueue<>();
+
+    @Override
+    protected Collection<ValidationResult> customValidate(ValidationContext 
validationContext) {
+        final Collection<ValidationResult> results = new 
ArrayList<ValidationResult>(1);
+        final String subscription = 
validationContext.getProperty(SUBSCRIPTION).evaluateAttributeExpressions().getValue();
+
+        try {
+            SubscriptionPath.parse(subscription);
+        } catch (ApiException e) {
+            results.add(new ValidationResult.Builder()
+                    .subject(SUBSCRIPTION.getName())
+                    .input(subscription)
+                    .valid(false)
+                    .explanation("The Suscription does not have a valid 
format.")
+                    .build());
+        }
+
+        return results;
+    }
+
+    @OnScheduled
+    public void onScheduled(ProcessContext context) {

Review comment:
       Consider `final` on the argument here

##########
File path: 
nifi-nar-bundles/nifi-gcp-bundle/nifi-gcp-processors/src/main/java/org/apache/nifi/processors/gcp/pubsub/lite/ConsumeGCPubSubLite.java
##########
@@ -0,0 +1,258 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.processors.gcp.pubsub.lite;
+
+import com.google.api.gax.core.FixedCredentialsProvider;
+import com.google.api.gax.rpc.ApiException;
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.cloud.pubsub.v1.MessageReceiver;
+import com.google.cloud.pubsublite.SubscriptionPath;
+import com.google.cloud.pubsublite.cloudpubsub.FlowControlSettings;
+import com.google.cloud.pubsublite.cloudpubsub.Subscriber;
+import com.google.cloud.pubsublite.cloudpubsub.SubscriberSettings;
+import com.google.common.collect.ImmutableList;
+import com.google.pubsub.v1.PubsubMessage;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.SeeAlso;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.annotation.lifecycle.OnStopped;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.DataUnit;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.processors.gcp.pubsub.AbstractGCPubSubProcessor;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_DESCRIPTION;
+
+@SeeAlso({PublishGCPubSubLite.class})
+@InputRequirement(InputRequirement.Requirement.INPUT_FORBIDDEN)
+@Tags({"google", "google-cloud", "gcp", "message", "pubsub", "consume", 
"lite"})
+@CapabilityDescription("Consumes message from the configured Google Cloud 
PubSub Lite subscription.")
+@WritesAttributes({
+        @WritesAttribute(attribute = MESSAGE_ID_ATTRIBUTE, description = 
MESSAGE_ID_DESCRIPTION),
+        @WritesAttribute(attribute = ORDERING_KEY_ATTRIBUTE, description = 
ORDERING_KEY_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_ATTRIBUTES_COUNT_ATTRIBUTE, 
description = MSG_ATTRIBUTES_COUNT_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_PUBLISH_TIME_ATTRIBUTE, description = 
MSG_PUBLISH_TIME_DESCRIPTION),
+        @WritesAttribute(attribute = DYNAMIC_ATTRIBUTES_ATTRIBUTE, description 
= DYNAMIC_ATTRIBUTES_DESCRIPTION)
+})
+public class ConsumeGCPubSubLite extends AbstractGCPubSubProcessor {
+
+    public static final PropertyDescriptor SUBSCRIPTION = new 
PropertyDescriptor.Builder()
+            .name("gcp-pubsub-subscription")
+            .displayName("Subscription")
+            .addValidator(StandardValidators.NON_EMPTY_EL_VALIDATOR)
+            .description("Name of the Google Cloud Pub/Sub Subscription. 
Example: 
projects/8476107443/locations/europe-west1-d/subscriptions/my-lite-subscription")
+            .required(true)
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .build();
+
+    public static final PropertyDescriptor BYTES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-bytes-outstanding")
+            .displayName("Bytes Outstanding")
+            .description("The number of quota bytes that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("10 MB")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.DATA_SIZE_VALIDATOR)
+            .build();
+
+    public static final PropertyDescriptor MESSAGES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-messages-outstanding")
+            .displayName("Messages Outstanding")
+            .description("The number of messages that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("1000")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.POSITIVE_INTEGER_VALIDATOR)
+            .build();
+
+    private Subscriber subscriber = null;
+    private static final BlockingQueue<Message> messages = new 
LinkedBlockingQueue<>();
+
+    @Override
+    protected Collection<ValidationResult> customValidate(ValidationContext 
validationContext) {
+        final Collection<ValidationResult> results = new 
ArrayList<ValidationResult>(1);
+        final String subscription = 
validationContext.getProperty(SUBSCRIPTION).evaluateAttributeExpressions().getValue();
+
+        try {
+            SubscriptionPath.parse(subscription);
+        } catch (ApiException e) {
+            results.add(new ValidationResult.Builder()
+                    .subject(SUBSCRIPTION.getName())
+                    .input(subscription)
+                    .valid(false)
+                    .explanation("The Suscription does not have a valid 
format.")
+                    .build());
+        }
+
+        return results;
+    }
+
+    @OnScheduled
+    public void onScheduled(ProcessContext context) {
+        try {
+            subscriber = getSubscriber(context);
+        } catch (Exception e) {
+            getLogger().error("Failed to create Google Cloud Subscriber", e);
+            throw new ProcessException(e);
+        }
+        try {
+            subscriber.startAsync().awaitRunning();
+        } catch (Exception e) {
+            getLogger().error("Failed to create Google Cloud Subscriber", 
subscriber.failureCause());
+            throw new ProcessException(e);
+        }
+    }
+
+    @OnStopped
+    public void onStopped() {
+        try {
+            if (subscriber != null) {
+                subscriber.stopAsync().awaitTerminated();
+            }
+        } catch (Exception e) {
+            getLogger().warn("Failed to gracefully shutdown the Google Cloud 
PubSub Lite Subscriber", e);
+        }
+    }
+
+    @Override
+    public List<PropertyDescriptor> getSupportedPropertyDescriptors() {
+        return ImmutableList.of(SUBSCRIPTION,
+                GCP_CREDENTIALS_PROVIDER_SERVICE,
+                BYTES_OUTSTANDING,
+                MESSAGES_OUTSTANDING);
+    }
+
+    @Override
+    public Set<Relationship> getRelationships() {
+        return Collections.singleton(REL_SUCCESS);
+    }
+
+    @Override
+    public void onTrigger(final ProcessContext context, final ProcessSession 
session) throws ProcessException {
+        if (subscriber == null) {
+            getLogger().error("Google Cloud PubSub Subscriber was not properly 
created. Yielding the processor...");
+            context.yield();
+            return;
+        }
+
+        if(!subscriber.isRunning()) {
+            getLogger().error("Google Cloud PubSub Subscriber is not running. 
Yielding the processor...", subscriber.failureCause());
+            throw new ProcessException(subscriber.failureCause());
+        }
+
+        Message message = messages.poll();
+        if(message == null) {
+            context.yield();
+            return;
+        }
+
+        FlowFile flowFile = session.create();
+
+        final Map<String, String> attributes = new HashMap<>();
+        attributes.put(MESSAGE_ID_ATTRIBUTE, 
message.getMessage().getMessageId());
+        attributes.put(ORDERING_KEY_ATTRIBUTE, 
message.getMessage().getOrderingKey());
+        attributes.put(MSG_ATTRIBUTES_COUNT_ATTRIBUTE, 
String.valueOf(message.getMessage().getAttributesCount()));
+        attributes.put(MSG_PUBLISH_TIME_ATTRIBUTE, 
String.valueOf(message.getMessage().getPublishTime().getSeconds()));
+        attributes.putAll(message.getMessage().getAttributesMap());
+
+        flowFile = session.putAllAttributes(flowFile, attributes);
+        flowFile = session.write(flowFile, out -> 
out.write(message.getMessage().getData().toStringUtf8().getBytes()));
+
+        session.transfer(flowFile, REL_SUCCESS);
+        session.getProvenanceReporter().receive(flowFile, 
context.getProperty(SUBSCRIPTION).evaluateAttributeExpressions().getValue());
+
+        message.getConsumer().ack();
+    }
+
+    private Subscriber getSubscriber(final ProcessContext context) throws 
IOException {
+
+        SubscriptionPath subscriptionPath = 
SubscriptionPath.parse(context.getProperty(SUBSCRIPTION).evaluateAttributeExpressions().getValue());
+
+        FlowControlSettings flowControlSettings = FlowControlSettings.builder()
+                
.setBytesOutstanding(context.getProperty(BYTES_OUTSTANDING).evaluateAttributeExpressions().asDataSize(DataUnit.B).longValue())
+                
.setMessagesOutstanding(context.getProperty(MESSAGES_OUTSTANDING).evaluateAttributeExpressions().asLong())
+                .build();
+
+        MessageReceiver receiver =
+                (PubsubMessage message, AckReplyConsumer consumer) -> {
+                    try {
+                        messages.put(new Message(message, consumer));
+                    } catch (InterruptedException e) {

Review comment:
       `final`

##########
File path: 
nifi-nar-bundles/nifi-gcp-bundle/nifi-gcp-processors/src/main/java/org/apache/nifi/processors/gcp/pubsub/lite/ConsumeGCPubSubLite.java
##########
@@ -0,0 +1,258 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.processors.gcp.pubsub.lite;
+
+import com.google.api.gax.core.FixedCredentialsProvider;
+import com.google.api.gax.rpc.ApiException;
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.cloud.pubsub.v1.MessageReceiver;
+import com.google.cloud.pubsublite.SubscriptionPath;
+import com.google.cloud.pubsublite.cloudpubsub.FlowControlSettings;
+import com.google.cloud.pubsublite.cloudpubsub.Subscriber;
+import com.google.cloud.pubsublite.cloudpubsub.SubscriberSettings;
+import com.google.common.collect.ImmutableList;
+import com.google.pubsub.v1.PubsubMessage;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.SeeAlso;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.annotation.lifecycle.OnStopped;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.DataUnit;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.processors.gcp.pubsub.AbstractGCPubSubProcessor;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_DESCRIPTION;
+
+@SeeAlso({PublishGCPubSubLite.class})
+@InputRequirement(InputRequirement.Requirement.INPUT_FORBIDDEN)
+@Tags({"google", "google-cloud", "gcp", "message", "pubsub", "consume", 
"lite"})
+@CapabilityDescription("Consumes message from the configured Google Cloud 
PubSub Lite subscription.")
+@WritesAttributes({
+        @WritesAttribute(attribute = MESSAGE_ID_ATTRIBUTE, description = 
MESSAGE_ID_DESCRIPTION),
+        @WritesAttribute(attribute = ORDERING_KEY_ATTRIBUTE, description = 
ORDERING_KEY_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_ATTRIBUTES_COUNT_ATTRIBUTE, 
description = MSG_ATTRIBUTES_COUNT_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_PUBLISH_TIME_ATTRIBUTE, description = 
MSG_PUBLISH_TIME_DESCRIPTION),
+        @WritesAttribute(attribute = DYNAMIC_ATTRIBUTES_ATTRIBUTE, description 
= DYNAMIC_ATTRIBUTES_DESCRIPTION)
+})
+public class ConsumeGCPubSubLite extends AbstractGCPubSubProcessor {
+
+    public static final PropertyDescriptor SUBSCRIPTION = new 
PropertyDescriptor.Builder()
+            .name("gcp-pubsub-subscription")
+            .displayName("Subscription")
+            .addValidator(StandardValidators.NON_EMPTY_EL_VALIDATOR)
+            .description("Name of the Google Cloud Pub/Sub Subscription. 
Example: 
projects/8476107443/locations/europe-west1-d/subscriptions/my-lite-subscription")
+            .required(true)
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .build();
+
+    public static final PropertyDescriptor BYTES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-bytes-outstanding")
+            .displayName("Bytes Outstanding")
+            .description("The number of quota bytes that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("10 MB")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.DATA_SIZE_VALIDATOR)
+            .build();
+
+    public static final PropertyDescriptor MESSAGES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-messages-outstanding")
+            .displayName("Messages Outstanding")
+            .description("The number of messages that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("1000")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.POSITIVE_INTEGER_VALIDATOR)
+            .build();
+
+    private Subscriber subscriber = null;
+    private static final BlockingQueue<Message> messages = new 
LinkedBlockingQueue<>();
+
+    @Override
+    protected Collection<ValidationResult> customValidate(ValidationContext 
validationContext) {
+        final Collection<ValidationResult> results = new 
ArrayList<ValidationResult>(1);
+        final String subscription = 
validationContext.getProperty(SUBSCRIPTION).evaluateAttributeExpressions().getValue();
+
+        try {
+            SubscriptionPath.parse(subscription);
+        } catch (ApiException e) {
+            results.add(new ValidationResult.Builder()
+                    .subject(SUBSCRIPTION.getName())
+                    .input(subscription)
+                    .valid(false)
+                    .explanation("The Suscription does not have a valid 
format.")
+                    .build());
+        }
+
+        return results;
+    }
+
+    @OnScheduled
+    public void onScheduled(ProcessContext context) {
+        try {
+            subscriber = getSubscriber(context);
+        } catch (Exception e) {
+            getLogger().error("Failed to create Google Cloud Subscriber", e);
+            throw new ProcessException(e);
+        }
+        try {
+            subscriber.startAsync().awaitRunning();
+        } catch (Exception e) {
+            getLogger().error("Failed to create Google Cloud Subscriber", 
subscriber.failureCause());
+            throw new ProcessException(e);
+        }
+    }
+
+    @OnStopped
+    public void onStopped() {
+        try {
+            if (subscriber != null) {
+                subscriber.stopAsync().awaitTerminated();
+            }
+        } catch (Exception e) {
+            getLogger().warn("Failed to gracefully shutdown the Google Cloud 
PubSub Lite Subscriber", e);
+        }
+    }
+
+    @Override
+    public List<PropertyDescriptor> getSupportedPropertyDescriptors() {
+        return ImmutableList.of(SUBSCRIPTION,
+                GCP_CREDENTIALS_PROVIDER_SERVICE,
+                BYTES_OUTSTANDING,
+                MESSAGES_OUTSTANDING);
+    }
+
+    @Override
+    public Set<Relationship> getRelationships() {
+        return Collections.singleton(REL_SUCCESS);
+    }
+
+    @Override
+    public void onTrigger(final ProcessContext context, final ProcessSession 
session) throws ProcessException {
+        if (subscriber == null) {
+            getLogger().error("Google Cloud PubSub Subscriber was not properly 
created. Yielding the processor...");
+            context.yield();
+            return;
+        }
+
+        if(!subscriber.isRunning()) {
+            getLogger().error("Google Cloud PubSub Subscriber is not running. 
Yielding the processor...", subscriber.failureCause());
+            throw new ProcessException(subscriber.failureCause());
+        }
+
+        Message message = messages.poll();
+        if(message == null) {

Review comment:
       Missing a space after `if`

##########
File path: 
nifi-nar-bundles/nifi-gcp-bundle/nifi-gcp-processors/src/main/java/org/apache/nifi/processors/gcp/pubsub/lite/ConsumeGCPubSubLite.java
##########
@@ -0,0 +1,258 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.processors.gcp.pubsub.lite;
+
+import com.google.api.gax.core.FixedCredentialsProvider;
+import com.google.api.gax.rpc.ApiException;
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.cloud.pubsub.v1.MessageReceiver;
+import com.google.cloud.pubsublite.SubscriptionPath;
+import com.google.cloud.pubsublite.cloudpubsub.FlowControlSettings;
+import com.google.cloud.pubsublite.cloudpubsub.Subscriber;
+import com.google.cloud.pubsublite.cloudpubsub.SubscriberSettings;
+import com.google.common.collect.ImmutableList;
+import com.google.pubsub.v1.PubsubMessage;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.SeeAlso;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.annotation.lifecycle.OnStopped;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.DataUnit;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.processors.gcp.pubsub.AbstractGCPubSubProcessor;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_DESCRIPTION;
+
+@SeeAlso({PublishGCPubSubLite.class})
+@InputRequirement(InputRequirement.Requirement.INPUT_FORBIDDEN)
+@Tags({"google", "google-cloud", "gcp", "message", "pubsub", "consume", 
"lite"})
+@CapabilityDescription("Consumes message from the configured Google Cloud 
PubSub Lite subscription.")
+@WritesAttributes({
+        @WritesAttribute(attribute = MESSAGE_ID_ATTRIBUTE, description = 
MESSAGE_ID_DESCRIPTION),
+        @WritesAttribute(attribute = ORDERING_KEY_ATTRIBUTE, description = 
ORDERING_KEY_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_ATTRIBUTES_COUNT_ATTRIBUTE, 
description = MSG_ATTRIBUTES_COUNT_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_PUBLISH_TIME_ATTRIBUTE, description = 
MSG_PUBLISH_TIME_DESCRIPTION),
+        @WritesAttribute(attribute = DYNAMIC_ATTRIBUTES_ATTRIBUTE, description 
= DYNAMIC_ATTRIBUTES_DESCRIPTION)
+})
+public class ConsumeGCPubSubLite extends AbstractGCPubSubProcessor {
+
+    public static final PropertyDescriptor SUBSCRIPTION = new 
PropertyDescriptor.Builder()
+            .name("gcp-pubsub-subscription")
+            .displayName("Subscription")
+            .addValidator(StandardValidators.NON_EMPTY_EL_VALIDATOR)
+            .description("Name of the Google Cloud Pub/Sub Subscription. 
Example: 
projects/8476107443/locations/europe-west1-d/subscriptions/my-lite-subscription")
+            .required(true)
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .build();
+
+    public static final PropertyDescriptor BYTES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-bytes-outstanding")
+            .displayName("Bytes Outstanding")
+            .description("The number of quota bytes that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("10 MB")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.DATA_SIZE_VALIDATOR)
+            .build();
+
+    public static final PropertyDescriptor MESSAGES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-messages-outstanding")
+            .displayName("Messages Outstanding")
+            .description("The number of messages that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("1000")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.POSITIVE_INTEGER_VALIDATOR)
+            .build();
+
+    private Subscriber subscriber = null;
+    private static final BlockingQueue<Message> messages = new 
LinkedBlockingQueue<>();
+
+    @Override
+    protected Collection<ValidationResult> customValidate(ValidationContext 
validationContext) {
+        final Collection<ValidationResult> results = new 
ArrayList<ValidationResult>(1);
+        final String subscription = 
validationContext.getProperty(SUBSCRIPTION).evaluateAttributeExpressions().getValue();
+
+        try {
+            SubscriptionPath.parse(subscription);
+        } catch (ApiException e) {

Review comment:
       Consider `final` on the exception here

##########
File path: 
nifi-nar-bundles/nifi-gcp-bundle/nifi-gcp-processors/src/main/java/org/apache/nifi/processors/gcp/pubsub/lite/ConsumeGCPubSubLite.java
##########
@@ -0,0 +1,258 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.processors.gcp.pubsub.lite;
+
+import com.google.api.gax.core.FixedCredentialsProvider;
+import com.google.api.gax.rpc.ApiException;
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.cloud.pubsub.v1.MessageReceiver;
+import com.google.cloud.pubsublite.SubscriptionPath;
+import com.google.cloud.pubsublite.cloudpubsub.FlowControlSettings;
+import com.google.cloud.pubsublite.cloudpubsub.Subscriber;
+import com.google.cloud.pubsublite.cloudpubsub.SubscriberSettings;
+import com.google.common.collect.ImmutableList;
+import com.google.pubsub.v1.PubsubMessage;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.SeeAlso;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.annotation.lifecycle.OnStopped;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.DataUnit;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.processors.gcp.pubsub.AbstractGCPubSubProcessor;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_DESCRIPTION;
+
+@SeeAlso({PublishGCPubSubLite.class})
+@InputRequirement(InputRequirement.Requirement.INPUT_FORBIDDEN)
+@Tags({"google", "google-cloud", "gcp", "message", "pubsub", "consume", 
"lite"})
+@CapabilityDescription("Consumes message from the configured Google Cloud 
PubSub Lite subscription.")
+@WritesAttributes({
+        @WritesAttribute(attribute = MESSAGE_ID_ATTRIBUTE, description = 
MESSAGE_ID_DESCRIPTION),
+        @WritesAttribute(attribute = ORDERING_KEY_ATTRIBUTE, description = 
ORDERING_KEY_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_ATTRIBUTES_COUNT_ATTRIBUTE, 
description = MSG_ATTRIBUTES_COUNT_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_PUBLISH_TIME_ATTRIBUTE, description = 
MSG_PUBLISH_TIME_DESCRIPTION),
+        @WritesAttribute(attribute = DYNAMIC_ATTRIBUTES_ATTRIBUTE, description 
= DYNAMIC_ATTRIBUTES_DESCRIPTION)
+})
+public class ConsumeGCPubSubLite extends AbstractGCPubSubProcessor {
+
+    public static final PropertyDescriptor SUBSCRIPTION = new 
PropertyDescriptor.Builder()
+            .name("gcp-pubsub-subscription")
+            .displayName("Subscription")
+            .addValidator(StandardValidators.NON_EMPTY_EL_VALIDATOR)
+            .description("Name of the Google Cloud Pub/Sub Subscription. 
Example: 
projects/8476107443/locations/europe-west1-d/subscriptions/my-lite-subscription")
+            .required(true)
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .build();
+
+    public static final PropertyDescriptor BYTES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-bytes-outstanding")
+            .displayName("Bytes Outstanding")
+            .description("The number of quota bytes that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("10 MB")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.DATA_SIZE_VALIDATOR)
+            .build();
+
+    public static final PropertyDescriptor MESSAGES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-messages-outstanding")
+            .displayName("Messages Outstanding")
+            .description("The number of messages that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("1000")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.POSITIVE_INTEGER_VALIDATOR)
+            .build();
+
+    private Subscriber subscriber = null;
+    private static final BlockingQueue<Message> messages = new 
LinkedBlockingQueue<>();
+
+    @Override
+    protected Collection<ValidationResult> customValidate(ValidationContext 
validationContext) {
+        final Collection<ValidationResult> results = new 
ArrayList<ValidationResult>(1);
+        final String subscription = 
validationContext.getProperty(SUBSCRIPTION).evaluateAttributeExpressions().getValue();
+
+        try {
+            SubscriptionPath.parse(subscription);
+        } catch (ApiException e) {
+            results.add(new ValidationResult.Builder()
+                    .subject(SUBSCRIPTION.getName())
+                    .input(subscription)
+                    .valid(false)
+                    .explanation("The Suscription does not have a valid 
format.")
+                    .build());
+        }
+
+        return results;
+    }
+
+    @OnScheduled
+    public void onScheduled(ProcessContext context) {
+        try {
+            subscriber = getSubscriber(context);
+        } catch (Exception e) {
+            getLogger().error("Failed to create Google Cloud Subscriber", e);
+            throw new ProcessException(e);
+        }
+        try {
+            subscriber.startAsync().awaitRunning();
+        } catch (Exception e) {
+            getLogger().error("Failed to create Google Cloud Subscriber", 
subscriber.failureCause());
+            throw new ProcessException(e);
+        }
+    }
+
+    @OnStopped
+    public void onStopped() {
+        try {
+            if (subscriber != null) {
+                subscriber.stopAsync().awaitTerminated();
+            }
+        } catch (Exception e) {
+            getLogger().warn("Failed to gracefully shutdown the Google Cloud 
PubSub Lite Subscriber", e);
+        }
+    }
+
+    @Override
+    public List<PropertyDescriptor> getSupportedPropertyDescriptors() {
+        return ImmutableList.of(SUBSCRIPTION,
+                GCP_CREDENTIALS_PROVIDER_SERVICE,
+                BYTES_OUTSTANDING,
+                MESSAGES_OUTSTANDING);
+    }
+
+    @Override
+    public Set<Relationship> getRelationships() {
+        return Collections.singleton(REL_SUCCESS);
+    }
+
+    @Override
+    public void onTrigger(final ProcessContext context, final ProcessSession 
session) throws ProcessException {
+        if (subscriber == null) {
+            getLogger().error("Google Cloud PubSub Subscriber was not properly 
created. Yielding the processor...");
+            context.yield();
+            return;
+        }
+
+        if(!subscriber.isRunning()) {
+            getLogger().error("Google Cloud PubSub Subscriber is not running. 
Yielding the processor...", subscriber.failureCause());
+            throw new ProcessException(subscriber.failureCause());
+        }
+
+        Message message = messages.poll();

Review comment:
       It looks like `message` could be `final` here.

##########
File path: 
nifi-nar-bundles/nifi-gcp-bundle/nifi-gcp-processors/src/main/java/org/apache/nifi/processors/gcp/pubsub/lite/PublishGCPubSubLite.java
##########
@@ -0,0 +1,279 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.processors.gcp.pubsub.lite;
+
+import com.google.api.core.ApiFuture;
+import com.google.api.core.ApiFutures;
+import com.google.api.gax.batching.BatchingSettings;
+import com.google.api.gax.core.FixedCredentialsProvider;
+import com.google.api.gax.rpc.ApiException;
+import com.google.cloud.pubsublite.TopicPath;
+import com.google.cloud.pubsublite.cloudpubsub.Publisher;
+import com.google.cloud.pubsublite.cloudpubsub.PublisherSettings;
+import com.google.common.collect.ImmutableList;
+import com.google.protobuf.ByteString;
+import com.google.protobuf.Timestamp;
+import com.google.pubsub.v1.PubsubMessage;
+
+import org.apache.nifi.annotation.behavior.DynamicProperty;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.SystemResource;
+import org.apache.nifi.annotation.behavior.SystemResourceConsideration;
+import org.apache.nifi.annotation.behavior.InputRequirement.Requirement;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.SeeAlso;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.annotation.lifecycle.OnStopped;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.DataUnit;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.processors.gcp.pubsub.AbstractGCPubSubProcessor;
+import org.threeten.bp.Duration;
+
+import java.io.ByteArrayOutputStream;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
+
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.TOPIC_NAME_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.TOPIC_NAME_DESCRIPTION;
+
+@SeeAlso({ConsumeGCPubSubLite.class})
+@InputRequirement(Requirement.INPUT_REQUIRED)
+@Tags({"google", "google-cloud", "gcp", "message", "pubsub", "publish", 
"lite"})
+@CapabilityDescription("Publishes the content of the incoming flowfile to the 
configured Google Cloud PubSub Lite topic. The processor supports dynamic 
properties." +
+        " If any dynamic properties are present, they will be sent along with 
the message in the form of 'attributes'.")
+@DynamicProperty(name = "Attribute name", value = "Value to be set to the 
attribute",
+        description = "Attributes to be set for the outgoing Google Cloud 
PubSub Lite message", expressionLanguageScope = 
ExpressionLanguageScope.FLOWFILE_ATTRIBUTES)
+@WritesAttributes({
+        @WritesAttribute(attribute = MESSAGE_ID_ATTRIBUTE, description = 
MESSAGE_ID_DESCRIPTION),
+        @WritesAttribute(attribute = TOPIC_NAME_ATTRIBUTE, description = 
TOPIC_NAME_DESCRIPTION)
+})
+@SystemResourceConsideration(resource = SystemResource.MEMORY, description = 
"The entirety of the FlowFile's content "
+        + "will be read into memory to be sent as a PubSub message.")
+public class PublishGCPubSubLite extends AbstractGCPubSubProcessor{
+
+    public static final PropertyDescriptor TOPIC_NAME = new 
PropertyDescriptor.Builder()
+            .name("gcp-pubsub-topic")
+            .displayName("Topic Name")
+            .description("Name of the Google Cloud PubSub Topic. Example: 
projects/8476107443/locations/europe-west1-d/topics/my-lite-topic")
+            .required(true)
+            .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .build();
+
+    public static final PropertyDescriptor BATCH_BYTES = new PropertyDescriptor
+            .Builder().name("gcp-batch-bytes")
+            .displayName("Batch Bytes Threshold")
+            .description("Publish request gets triggered based on this Batch 
Bytes Threshold property and"
+                    + " the " + BATCH_SIZE.getDisplayName() + " property, 
whichever condition is met first.")
+            .required(true)
+            .defaultValue("3 MB")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.DATA_SIZE_VALIDATOR)
+            .build();
+
+    private Publisher publisher = null;
+
+    @Override
+    public List<PropertyDescriptor> getSupportedPropertyDescriptors() {
+        return ImmutableList.of(TOPIC_NAME,
+                GCP_CREDENTIALS_PROVIDER_SERVICE,
+                BATCH_SIZE,
+                BATCH_BYTES);
+    }
+
+    @Override
+    protected PropertyDescriptor getSupportedDynamicPropertyDescriptor(final 
String propertyDescriptorName) {
+        return new PropertyDescriptor.Builder()
+                .required(false)
+                .name(propertyDescriptorName)
+                .displayName(propertyDescriptorName)
+                
.addValidator(StandardValidators.ATTRIBUTE_KEY_PROPERTY_NAME_VALIDATOR)
+                .dynamic(true)
+                
.expressionLanguageSupported(ExpressionLanguageScope.FLOWFILE_ATTRIBUTES)
+                .build();
+    }
+
+    @Override
+    public Set<Relationship> getRelationships() {
+        return Collections.unmodifiableSet(
+                new HashSet<>(Arrays.asList(REL_SUCCESS, REL_FAILURE))
+        );
+    }
+
+    @Override
+    protected Collection<ValidationResult> customValidate(ValidationContext 
validationContext) {
+        final Collection<ValidationResult> results = new 
ArrayList<ValidationResult>(1);
+        final String topic = 
validationContext.getProperty(TOPIC_NAME).evaluateAttributeExpressions().getValue();
+
+        try {
+            TopicPath.parse(topic);
+        } catch (ApiException e) {
+            results.add(new ValidationResult.Builder()
+                    .subject(TOPIC_NAME.getName())
+                    .input(topic)
+                    .valid(false)
+                    .explanation("The Topic does not have a valid format.")
+                    .build());
+        }
+
+        return results;
+    }
+
+    @Override
+    @OnScheduled
+    public void onScheduled(ProcessContext context) {
+        try {
+            publisher = getPublisher(context);
+        } catch (Exception e) {
+            getLogger().error("Failed to create Google Cloud PubSub Lite 
Publisher", e);
+            throw new ProcessException(e);
+        }

Review comment:
       Another good `VerifiableProcessor` implementation

##########
File path: 
nifi-nar-bundles/nifi-gcp-bundle/nifi-gcp-processors/src/main/java/org/apache/nifi/processors/gcp/pubsub/lite/PublishGCPubSubLite.java
##########
@@ -0,0 +1,279 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.processors.gcp.pubsub.lite;
+
+import com.google.api.core.ApiFuture;
+import com.google.api.core.ApiFutures;
+import com.google.api.gax.batching.BatchingSettings;
+import com.google.api.gax.core.FixedCredentialsProvider;
+import com.google.api.gax.rpc.ApiException;
+import com.google.cloud.pubsublite.TopicPath;
+import com.google.cloud.pubsublite.cloudpubsub.Publisher;
+import com.google.cloud.pubsublite.cloudpubsub.PublisherSettings;
+import com.google.common.collect.ImmutableList;
+import com.google.protobuf.ByteString;
+import com.google.protobuf.Timestamp;
+import com.google.pubsub.v1.PubsubMessage;
+
+import org.apache.nifi.annotation.behavior.DynamicProperty;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.SystemResource;
+import org.apache.nifi.annotation.behavior.SystemResourceConsideration;
+import org.apache.nifi.annotation.behavior.InputRequirement.Requirement;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.SeeAlso;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.annotation.lifecycle.OnStopped;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.DataUnit;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.processors.gcp.pubsub.AbstractGCPubSubProcessor;
+import org.threeten.bp.Duration;
+
+import java.io.ByteArrayOutputStream;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
+
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.TOPIC_NAME_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.TOPIC_NAME_DESCRIPTION;
+
+@SeeAlso({ConsumeGCPubSubLite.class})
+@InputRequirement(Requirement.INPUT_REQUIRED)
+@Tags({"google", "google-cloud", "gcp", "message", "pubsub", "publish", 
"lite"})
+@CapabilityDescription("Publishes the content of the incoming flowfile to the 
configured Google Cloud PubSub Lite topic. The processor supports dynamic 
properties." +
+        " If any dynamic properties are present, they will be sent along with 
the message in the form of 'attributes'.")
+@DynamicProperty(name = "Attribute name", value = "Value to be set to the 
attribute",
+        description = "Attributes to be set for the outgoing Google Cloud 
PubSub Lite message", expressionLanguageScope = 
ExpressionLanguageScope.FLOWFILE_ATTRIBUTES)
+@WritesAttributes({
+        @WritesAttribute(attribute = MESSAGE_ID_ATTRIBUTE, description = 
MESSAGE_ID_DESCRIPTION),
+        @WritesAttribute(attribute = TOPIC_NAME_ATTRIBUTE, description = 
TOPIC_NAME_DESCRIPTION)
+})
+@SystemResourceConsideration(resource = SystemResource.MEMORY, description = 
"The entirety of the FlowFile's content "
+        + "will be read into memory to be sent as a PubSub message.")
+public class PublishGCPubSubLite extends AbstractGCPubSubProcessor{
+
+    public static final PropertyDescriptor TOPIC_NAME = new 
PropertyDescriptor.Builder()
+            .name("gcp-pubsub-topic")
+            .displayName("Topic Name")
+            .description("Name of the Google Cloud PubSub Topic. Example: 
projects/8476107443/locations/europe-west1-d/topics/my-lite-topic")
+            .required(true)
+            .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .build();
+
+    public static final PropertyDescriptor BATCH_BYTES = new PropertyDescriptor
+            .Builder().name("gcp-batch-bytes")
+            .displayName("Batch Bytes Threshold")
+            .description("Publish request gets triggered based on this Batch 
Bytes Threshold property and"
+                    + " the " + BATCH_SIZE.getDisplayName() + " property, 
whichever condition is met first.")
+            .required(true)
+            .defaultValue("3 MB")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.DATA_SIZE_VALIDATOR)
+            .build();
+
+    private Publisher publisher = null;
+
+    @Override
+    public List<PropertyDescriptor> getSupportedPropertyDescriptors() {
+        return ImmutableList.of(TOPIC_NAME,
+                GCP_CREDENTIALS_PROVIDER_SERVICE,
+                BATCH_SIZE,
+                BATCH_BYTES);
+    }
+
+    @Override
+    protected PropertyDescriptor getSupportedDynamicPropertyDescriptor(final 
String propertyDescriptorName) {
+        return new PropertyDescriptor.Builder()
+                .required(false)
+                .name(propertyDescriptorName)
+                .displayName(propertyDescriptorName)
+                
.addValidator(StandardValidators.ATTRIBUTE_KEY_PROPERTY_NAME_VALIDATOR)
+                .dynamic(true)
+                
.expressionLanguageSupported(ExpressionLanguageScope.FLOWFILE_ATTRIBUTES)
+                .build();
+    }
+
+    @Override
+    public Set<Relationship> getRelationships() {
+        return Collections.unmodifiableSet(
+                new HashSet<>(Arrays.asList(REL_SUCCESS, REL_FAILURE))
+        );
+    }
+
+    @Override
+    protected Collection<ValidationResult> customValidate(ValidationContext 
validationContext) {

Review comment:
       Look for additional places to add `final` in this class as well

##########
File path: 
nifi-nar-bundles/nifi-gcp-bundle/nifi-gcp-processors/src/main/java/org/apache/nifi/processors/gcp/pubsub/lite/ConsumeGCPubSubLite.java
##########
@@ -0,0 +1,258 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.processors.gcp.pubsub.lite;
+
+import com.google.api.gax.core.FixedCredentialsProvider;
+import com.google.api.gax.rpc.ApiException;
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.cloud.pubsub.v1.MessageReceiver;
+import com.google.cloud.pubsublite.SubscriptionPath;
+import com.google.cloud.pubsublite.cloudpubsub.FlowControlSettings;
+import com.google.cloud.pubsublite.cloudpubsub.Subscriber;
+import com.google.cloud.pubsublite.cloudpubsub.SubscriberSettings;
+import com.google.common.collect.ImmutableList;
+import com.google.pubsub.v1.PubsubMessage;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.SeeAlso;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.annotation.lifecycle.OnStopped;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.DataUnit;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.processors.gcp.pubsub.AbstractGCPubSubProcessor;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.DYNAMIC_ATTRIBUTES_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MESSAGE_ID_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_ATTRIBUTES_COUNT_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.MSG_PUBLISH_TIME_DESCRIPTION;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_ATTRIBUTE;
+import static 
org.apache.nifi.processors.gcp.pubsub.PubSubAttributes.ORDERING_KEY_DESCRIPTION;
+
+@SeeAlso({PublishGCPubSubLite.class})
+@InputRequirement(InputRequirement.Requirement.INPUT_FORBIDDEN)
+@Tags({"google", "google-cloud", "gcp", "message", "pubsub", "consume", 
"lite"})
+@CapabilityDescription("Consumes message from the configured Google Cloud 
PubSub Lite subscription.")
+@WritesAttributes({
+        @WritesAttribute(attribute = MESSAGE_ID_ATTRIBUTE, description = 
MESSAGE_ID_DESCRIPTION),
+        @WritesAttribute(attribute = ORDERING_KEY_ATTRIBUTE, description = 
ORDERING_KEY_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_ATTRIBUTES_COUNT_ATTRIBUTE, 
description = MSG_ATTRIBUTES_COUNT_DESCRIPTION),
+        @WritesAttribute(attribute = MSG_PUBLISH_TIME_ATTRIBUTE, description = 
MSG_PUBLISH_TIME_DESCRIPTION),
+        @WritesAttribute(attribute = DYNAMIC_ATTRIBUTES_ATTRIBUTE, description 
= DYNAMIC_ATTRIBUTES_DESCRIPTION)
+})
+public class ConsumeGCPubSubLite extends AbstractGCPubSubProcessor {
+
+    public static final PropertyDescriptor SUBSCRIPTION = new 
PropertyDescriptor.Builder()
+            .name("gcp-pubsub-subscription")
+            .displayName("Subscription")
+            .addValidator(StandardValidators.NON_EMPTY_EL_VALIDATOR)
+            .description("Name of the Google Cloud Pub/Sub Subscription. 
Example: 
projects/8476107443/locations/europe-west1-d/subscriptions/my-lite-subscription")
+            .required(true)
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .build();
+
+    public static final PropertyDescriptor BYTES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-bytes-outstanding")
+            .displayName("Bytes Outstanding")
+            .description("The number of quota bytes that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("10 MB")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.DATA_SIZE_VALIDATOR)
+            .build();
+
+    public static final PropertyDescriptor MESSAGES_OUTSTANDING = new 
PropertyDescriptor
+            .Builder().name("gcp-messages-outstanding")
+            .displayName("Messages Outstanding")
+            .description("The number of messages that may be outstanding to 
the client.")
+            .required(true)
+            .defaultValue("1000")
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .addValidator(StandardValidators.POSITIVE_INTEGER_VALIDATOR)
+            .build();
+
+    private Subscriber subscriber = null;
+    private static final BlockingQueue<Message> messages = new 
LinkedBlockingQueue<>();
+
+    @Override
+    protected Collection<ValidationResult> customValidate(ValidationContext 
validationContext) {
+        final Collection<ValidationResult> results = new 
ArrayList<ValidationResult>(1);
+        final String subscription = 
validationContext.getProperty(SUBSCRIPTION).evaluateAttributeExpressions().getValue();
+
+        try {
+            SubscriptionPath.parse(subscription);
+        } catch (ApiException e) {
+            results.add(new ValidationResult.Builder()
+                    .subject(SUBSCRIPTION.getName())
+                    .input(subscription)
+                    .valid(false)
+                    .explanation("The Suscription does not have a valid 
format.")
+                    .build());
+        }
+
+        return results;
+    }
+
+    @OnScheduled
+    public void onScheduled(ProcessContext context) {
+        try {
+            subscriber = getSubscriber(context);
+        } catch (Exception e) {
+            getLogger().error("Failed to create Google Cloud Subscriber", e);
+            throw new ProcessException(e);
+        }

Review comment:
       If you'd like to implement `VerifiableProcessor`, this would be a great 
test for the `#verify` method.  If so, it would be nice to rebase on main in 
order to pull in NIFI-9288.




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