public void setMultipleSink(boolean multipleSink) {
            this.multipleSink = multipleSink;
        }
Sets a REST client factory for custom client configuration.

@param restClientFactory the factory that configures the rest client.
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/elasticsearch-7/src/main/java/org/apache/inlong/sort/elasticsearch7/ElasticsearchSink.java