@Override
    protected SourceSplitState initializedState(SourceSplitBase split) {
        if (split.isSnapshotSplit()) {
            return new SnapshotSplitState(split.asSnapshotSplit());
        } else {
            return new StreamSplitState(split.asStreamSplit());
        }
    }
The multi-parallel source reader for table snapshot phase from {@link SnapshotSplit} and then
single-parallel source reader for table stream phase from {@link StreamSplit}.
Copy from com.ververica:flink-cdc-base:2.3.0.
inlong-sort/sort-flink/cdc-base/src/main/java/org/apache/inlong/sort/cdc/base/source/reader/IncrementalSourceReader.java