cbornet commented on code in PR #16816:
URL: https://github.com/apache/pulsar/pull/16816#discussion_r949932680


##########
site2/docs/functions-develop-api.md:
##########
@@ -102,6 +102,39 @@ public class ExclamationFunction implements 
Function<String, String> {
 
 For more details, see [code 
example](https://github.com/apache/pulsar/blob/master/pulsar-functions/java-examples/src/main/java/org/apache/pulsar/functions/api/examples/ExclamationFunction.java).
 
+The return type of the `Function` can be wrapped in a Pulsar `Record` generic 
which gives more control on the output message (topic, schema, properties, ...)
+You can use the `Context::newOutputRecordBuilder` method to build this 
`Record` output.
+
+```java
+
+import java.util.HashMap;
+import java.util.Map;
+import org.apache.pulsar.functions.api.Context;
+import org.apache.pulsar.functions.api.Function;
+import org.apache.pulsar.functions.api.Record;
+
+public class RecordFunction implements Function<String, Record<String>> {
+
+    @Override
+    public Record<String> process(String input, Context context) throws 
Exception {
+        String publishTopic = (String) 
context.getUserConfigValueOrDefault("publish-topic", "publishtopic");

Review Comment:
   I removed the destinationTopic part.



##########
site2/docs/functions-develop-api.md:
##########
@@ -102,6 +102,39 @@ public class ExclamationFunction implements 
Function<String, String> {
 
 For more details, see [code 
example](https://github.com/apache/pulsar/blob/master/pulsar-functions/java-examples/src/main/java/org/apache/pulsar/functions/api/examples/ExclamationFunction.java).
 
+The return type of the function can be wrapped in a `Record` generic which 
gives you more control over the output messages, such as topics, schemas, 
properties, and so on.
+Use the `Context::newOutputRecordBuilder` method to build this `Record` output.
+
+```java
+
+import java.util.HashMap;
+import java.util.Map;
+import org.apache.pulsar.functions.api.Context;
+import org.apache.pulsar.functions.api.Function;
+import org.apache.pulsar.functions.api.Record;
+
+public class RecordFunction implements Function<String, Record<String>> {
+
+    @Override
+    public Record<String> process(String input, Context context) throws 
Exception {
+        String publishTopic = (String) 
context.getUserConfigValueOrDefault("publish-topic", "publishtopic");
+        String output = String.format("%s!", input);
+
+        Map<String, String> properties = new 
HashMap<>(context.getCurrentRecord().getProperties());
+        context.getCurrentRecord().getTopicName().ifPresent(topic -> 
properties.put("input_topic", topic));
+
+        return context.<String>newOutputRecordBuilder()

Review Comment:
   done



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