[FEATURE] Allow Response Objects and Exceptions to Access Http Response Headers

Is your feature request related to a problem?

A clear and concise description of what the problem is, e.g. I'm always frustrated when [...].

I am using the OpenSearchClient with the AwsSdk2Transport, and I cannot retrieve the http headers in the response. This makes it very hard for me to debug issues with my service provider as I cannot provide them request ids.

What solution would you like?

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I would like for two changes:

1. All response headers should be available on response objects exposed via a method such as getResponseHeaders().
2. All exceptions thrown because of a response error should also include the http headers from that response. I propose a class: OpenSearchResponseException to encapsulate this behavior.

What alternatives have you considered?

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I could not figure out a way to accomplish this by subclassing and overriding code in this package. I would need to migrate to a RestClient or ApacheHttpClient, implement Sigv4 signing, and do my own response parsing.

Do you have any additional context?

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Here looks to be where the response is de-serialized and where headers are lost:

https://github.com/opensearch-project/opensearch-java/blob/main/java-client/src/main/java/org/opensearch/client/transport/aws/AwsSdk2Transport.java#L619-L636