@Override
    public boolean isEmpty() {
        return wrapperSet.isEmpty();
    }
Copied from iceberg 1.1.x. Modify Set to concurrent Set.
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/iceberg/src/main/java/org/apache/inlong/sort/iceberg/sink/trick/CharSequenceSet.java