@Override
  public void close() throws IOException {
    continuousSplitPlanner.close();
    splitAssigner.close();
    super.close();
  }
Check whether all first splits have been finished or not. After all finished, enumerator will
send a {@link InitializationFinishedEvent} to notify all {@link MixedFormatSourceReader}.

@param finishedSplitIds
amoro-format-mixed/amoro-mixed-flink/amoro-mixed-flink-common/src/main/java/org/apache/amoro/flink/read/hybrid/enumerator/MixedFormatSourceEnumerator.java