@Override
    public void close() throws Exception {
        if (currentFetcher != null) {
            LOG.info("Close current fetcher {}", currentFetcher.getClass().getCanonicalName());
            currentFetcher.close();
            currentSplitId = null;
        }
    }
Basic class read {@link SourceSplitBase} and return {@link SourceRecord}.
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/IncrementalSourceSplitReader.java