[PR] [Java SDK] Add ValueState.read(T defaultValue) overload [beam]

Wed, 11 Mar 2026 04:50:10 -0700 


Ri1a opened a new pull request, #37824:
URL: https://github.com/apache/beam/pull/37824

   Fixes #18174
   
   This change adds a convenience overload `ValueState.read(T defaultValue)` to 
simplify handling of uninitialized state. Currently, `ValueState.read()` 
returns `null` if the value has never been written. As a result, users 
frequently need to write boilerplate code such as:
   
   ```java
   Integer count = state.read();
   if (count == null) {
     count = 0;
   }
   ```
   
   or:
   
   ```java
   Integer count = MoreObjects.firstNonNull(state.read(), 0);
   ```
   
   This PR introduces a default method:
   
   ```java
   default T read(T defaultValue)
   ```
   
   which returns the stored value if present, or `defaultValue` if the state 
has not been written yet.
   
   ### Tests
   
   Added `ValueStateTest` to verify:
   
   * `read(defaultValue)` returns the default when the state is empty
   * `read(defaultValue)` returns the stored value when present
   * `readLater()` continues to return the same state instance
   
   ### Compatibility
   
   This change is fully backward compatible:
   
   * existing implementations of `ValueState` do not need modification
   * the new method is implemented as a Java 8 default interface method
   
   ---
   
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