private void offerEOF() {
        try {
            offer(new SinkBufferEntity(null, null, null).asEOF());
        } catch (Exception e) {
            LOGGER.warn("Writing EOF failed.", e);
        }
    }
async flush

@return false if met eof and flush thread will exit.
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/starrocks/src/main/java/org/apache/inlong/sort/starrocks/manager/StarRocksSinkManager.java