@Override
  public void handleSplitRequest(int subtaskId, @Nullable String requesterHostname) {
    throw new UnsupportedOperationException(
        String.format(
            "Received invalid default split request event "
                + "from subtask %d as mixed-format source uses custom split request event",
            subtaskId));
  }
The abstract mixed-format source enumerator.
amoro-format-mixed/amoro-mixed-flink/amoro-mixed-flink-common/src/main/java/org/apache/amoro/flink/read/hybrid/enumerator/AbstractMixedFormatEnumerator.java