public void setBulkFlushBackoffDelay(long delayMillis) {
            Preconditions.checkArgument(
                    delayMillis >= 0,
                    "Delay (in milliseconds) between each backoff attempt must be larger than or equal to 0.");
            this.bulkRequestsConfig.put(
                    CONFIG_KEY_BULK_FLUSH_BACKOFF_DELAY, String.valueOf(delayMillis));
        }
Sets the amount of delay between each backoff attempt when flushing bulk requests, in
milliseconds.

@param delayMillis the amount of delay between each backoff attempt when flushing bulk
        requests, in milliseconds.
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/elasticsearch-7/src/main/java/org/apache/inlong/sort/elasticsearch7/ElasticsearchSink.java