[hotfix][DataStream API] Fix checkstyle issues and JavaDocs in Checkp…

…ointListener.

flink-runtime/src/main/java/org/apache/flink/runtime/state/CheckpointListener.java

@@ -15,8 +15,8 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.apache.flink.runtime.state;
 
+package org.apache.flink.runtime.state;
 
 import org.apache.flink.annotation.PublicEvolving;
 
@@ -30,20 +30,22 @@ public interface CheckpointListener {
 
  /**
  * This method is called as a notification once a distributed checkpoint has been completed.
- * 
- * Note that any exception during this method will not cause the checkpoint to
+ *
+ * <p>Note that any exception during this method will not cause the checkpoint to
  * fail any more.
- * 
+ *
  * @param checkpointId The ID of the checkpoint that has been completed.
- * @throws Exception
+ * @throws Exception This method can propagate exceptions, which leads to a failure/recovery for
+ * the task. Not that this will NOT lead to the checkpoint being revoked.
  */
  void notifyCheckpointComplete(long checkpointId) throws Exception;
 
  /**
  * This method is called as a notification once a distributed checkpoint has been aborted.
  *
  * @param checkpointId The ID of the checkpoint that has been aborted.
- * @throws Exception
+ * @throws Exception This method can propagate exceptions, which leads to a failure/recovery for
+ * the task.
  */
- default void notifyCheckpointAborted(long checkpointId) throws Exception {};
+ default void notifyCheckpointAborted(long checkpointId) throws Exception {}
 }