I got similar issue before even though we're using both 6.x server & client, reported on the forum but didn't get any feedback. As I'm using org.elasticsearch.action.bulk.BulkProcessor, for which alternatively you can set the number of retries through BulkProcessor.Builder.setBackoffPolicy() (example at https://www.elastic.co/guide/en/elasticsearch/client/java-rest/master/java-rest-high-document-bulk.html#java-rest-high-document-bulk-processor). However, for you to be aware of, there is another bug on the BulkProcessor reported at BulkProcessor hangs instead of timeout, which doesn't seem resolved yet 
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