[hotfix][chck] Remove Nullable annotation from method with primitive …

…return type

ZooKeeperStateHandleStore#releaseAndTryRemove returns a primitive boolean and, thus,
does not need a @nullable annotation.

flink-runtime/src/main/java/org/apache/flink/runtime/zookeeper/ZooKeeperStateHandleStore.java

@@ -31,8 +31,6 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import javax.annotation.Nullable;
-
 import java.io.IOException;
 import java.io.Serializable;
 import java.util.ArrayList;
@@ -328,7 +326,6 @@ public List<Tuple2<RetrievableStateHandle<T>, String>> getAllAndLock() throws Ex
  * @return True if the state handle could be released
  * @throws Exception If the ZooKeeper operation or discarding the state handle fails
  */
- @Nullable
  public boolean releaseAndTryRemove(String pathInZooKeeper) throws Exception {
  checkNotNull(pathInZooKeeper, "Path in ZooKeeper");