in flink-connector-opensearch/src/main/java/org/apache/flink/streaming/connectors/opensearch/OpensearchSink.java [351:360]
public void snapshotState(FunctionSnapshotContext context) throws Exception {
checkAsyncErrorsAndRequests();
if (flushOnCheckpoint) {
while (numPendingRequests.get() != 0) {
bulkProcessor.flush();
checkAsyncErrorsAndRequests();
}
}
}