Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/2094#discussion_r84765869
--- Diff:
flink-core/src/main/java/org/apache/flink/api/java/typeutils/FieldAccessor.java
---
@@ -0,0 +1,324 @@
+/*
+ * 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.flink.api.java.typeutils;
+
+import org.apache.flink.annotation.PublicEvolving;
+import org.apache.flink.api.common.operators.Keys;
+import org.apache.flink.api.common.typeinfo.BasicTypeInfo;
+import org.apache.flink.api.common.typeinfo.InvalidFieldReferenceException;
+import org.apache.flink.api.common.typeinfo.TypeInformation;
+import org.apache.flink.api.java.tuple.Tuple;
+import org.apache.flink.api.java.typeutils.runtime.FieldSerializer;
+
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.Serializable;
+import java.lang.reflect.Array;
+import java.lang.reflect.Field;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static org.apache.flink.util.Preconditions.checkNotNull;
+
+
+/**
+ * These classes encapsulate the logic of accessing a field specified by
the user as either an index
+ * or a field expression string. TypeInformation can also be requested for
the field.
+ * The position index might specify a field of a Tuple, an array, or a
simple type (only "0th field").
+ *
+ * Field expressions that specify nested fields (e.g. "f1.a.foo") result
in nested field accessors.
+ * These penetrate one layer, and then delegate the rest of the work to an
"innerAccesor".
+ * (see PojoFieldAccessor, RecursiveTupleFieldAccessor,
ProductFieldAccessor)
+ */
+@PublicEvolving
--- End diff --
`FieldAccessor` was `@Internal` before.
Why changing it to `@PublicEvolving`?
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastruct...@apache.org or file a JIRA ticket
with INFRA.
---
