Github user bowenli86 commented on a diff in the pull request:
https://github.com/apache/flink/pull/4963#discussion_r159565645
--- Diff:
flink-core/src/main/java/org/apache/flink/api/common/state/ListState.java ---
@@ -33,4 +35,14 @@
* @param <T> Type of values that this list state keeps.
*/
@PublicEvolving
-public interface ListState<T> extends MergingState<T, Iterable<T>> {}
+public interface ListState<T> extends MergingState<T, Iterable<T>> {
+ /**
+ * Updates the state of the current key for the given source namespaces
into the state of
+ * the target namespace.
+ *
+ * @param values The target namespace where the merged state should be
stored.
+ *
+ * @throws Exception The method may forward exception thrown internally
(by I/O or functions).
+ */
+ void update(List<T> values) throws Exception;
--- End diff --
Let me document it. They are of the same result - return `null` when given
an empty list
---
