618 withjson support method for put index template request

[pranishd1]

Description

Added "withJson" support for PutIndexTemplateRequest

Issues Resolved

Closes [#618]

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[dblock]

There are a lot of requests that support JSON bodies. I think we need to introduce a class or train that supports withJson at a lower level than PutIndexTemplateRequest and then include that in it. WDYT?

[pranishd1]

Yes, that would be great. I will look into that.

[VachaShah]

@pranishd1 Can you fix merge conflicts please? Also, you might have to run ./gradlew spotlessApply to fix formatting.

[VachaShah]

Can we also mention in the USER_GUIDE that how to use withJson?

[dblock]

This is a lot better! Can we apply this to at least some minimum number of requests, not just put index template? I'd also love a guide (maybe copy from opensearch-project/opensearch-py#542?) and a working sample as part of this PR, please?

[pranishd1]

Can we also mention in the USER_GUIDE that how to use withJson?

sure, I will add a section about how to use this to the user guide.

[pranishd1]

This is a lot better! Can we apply this to at least some minimum number of requests, not just put index template? I'd also love a guide (maybe copy from opensearch-project/opensearch-py#542?) and a working sample as part of this PR, please?

Yeah, sure I will add this to a few other requests. Thanks for the feedback.

[dblock]

@pranishd1 Want to finish this?

[pranishd1]

@dblock , sorry about the delay. I am in the process of implementing the interface in create, search and delete requests. While doing so, I am stuck at object deserialization process. This method does not cover all the objects.

[Jai2305]

Thanks for this guys, much needed, do you need any help with this?
Also after reading the code I got to know the problem -
that as of now we rely on static deserializer which creates a new builder everytime, referring to this code exactly -

public static final JsonpDeserializer<SearchRequest> _DESERIALIZER = ObjectBuilderDeserializer.lazy(
        Builder::new,
        SearchRequest::setupSearchRequestDeserializer
    );

Although some suggestions -

• Can you please also create a method which takes Readable as an argument kind of like

 default<T> B withJson(Reader reader) {
             ........ 

• Also now that we have default mapper in JsonpUtils, we can use that rather than relying on a specific implementation
  please refer here .

[dblock]

@Jai2305 looks like the PR hasn't been touched in a long time, so yes, would love it if you could pick it up and finish it!

Note that we added support for a generic interface since which takes/returns raw JSON, so some parts of that may be reusable.

[Xtansia]

A version of this was added in #1148, documented here: https://github.com/opensearch-project/opensearch-java/blob/main/guides/json.md#using-withjson