@Override
  protected void onSplitFinished(Map<String, MixedFormatSplitState> finishedSplitIds) {
    requestSplit(Lists.newArrayList(finishedSplitIds.keySet()));
  }
SourceEvents may be received before this#pollNext.
amoro-format-mixed/amoro-mixed-flink/amoro-mixed-flink-common/src/main/java/org/apache/amoro/flink/read/hybrid/reader/MixedFormatSourceReader.java