private void notifyReaders() {
    LOG.info("all splits finished, send events to readers");
    IntStream.range(0, context.currentParallelism())
        .forEach(i -> context.sendEventToSourceReader(i, InitializationFinishedEvent.INSTANCE));
    temporalJoinSplits.clear();
    temporalJoinSplits.notifyReader();
  }
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