@Override
	public void onFailure(ActionRequest action, Throwable failure, int restStatusCode, RequestIndexer indexer) {
		// ignore failure
	}
Ignores all kinds of failures and drops the affected {@link ActionRequest}.
elasticsearch5-xh/elasticsearch5-xh-sink/src/main/java/org/apache/flink/streaming/connectors/elasticsearch/util/IgnoringFailureHandler.java