Elasticsearch concurrent request handling with optimistic locking in Java UpdateRequest with Upsert

[blackOcean (Sagar Rout)]

Concurrent request handling

I have one use case where application can get concurrent requests to update single document.
Earlier I was using IndexRequest with External versionining but IndexRequest I was facing problem that it was replacing the old document with new document rather than updating old document.

        <dependency>
        <groupId>org.elasticsearch.client</groupId>
        <artifactId>elasticsearch-rest-high-level-client</artifactId>
        <version>7.1.1</version>
    </dependency>

    <dependency>
        <groupId>org.elasticsearch</groupId>
        <artifactId>elasticsearch</artifactId>
        <version>7.1.1</version>
    </dependency>

But with IndexRequest external versioning was working but to be honest I find it bit cumbersome.

Neverthless, Now I thought to use UpdateRequest which will create the document with givenId or update the document(rather than replacning).

        UpdateRequest updateRequest = new UpdateRequest(elasticSearchConfiguration.getIndexName(), id);
        updateRequest.doc(objectMapper.convertValue(object, Map.class));
        updateRequest.docAsUpsert(true);
        updateRequest.setRefreshPolicy(WriteRequest.RefreshPolicy.IMMEDIATE);
        restHighLevelClient.update(updateRequest, RequestOptions.DEFAULT);

I am not able to understand how elasticsearch API will handles the concurrent request and throw VersionConflict exception. As per my initial testing, I don't think UpdateRequest is helping .

Any help would be great like how to best handle the concurrent request with elasticsearch (if possible not manual optimistic locking)