rename fields to snake case

[sachinda-git]

This pull request addresses issue #16334 by renaming the following fields in the SnapshotRecoverySource class to follow a standard snake_case naming convention:

isSearchableSnapshot → is_searchable_snapshot
remoteStoreIndexShallowCopy → remote_store_index_shallow_copy
sourceRemoteStoreRepository → source_remote_store_repository
sourceRemoteTranslogRepository → source_remote_translog_repository
The changes ensure consistency in field naming, improving clarity and alignment with API standards. All affected methods, constructors, and serialization logic have been updated accordingly.

Related Issues
Resolves #16334

Check List
Functionality includes testing: Updated relevant unit tests to reflect the changes.
API changes companion pull request created, if applicable.
Public documentation issue/PR created, if applicable.
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[github-actions]

❌ Gradle check result for c4ef85b: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[cwperks]

Java variables should follow the lowerCamelCase convention, but when serialized in toXContent (as done on the left side of this line), these can be converted to lower_snake_case.

As @gbbafna pointed out here, since this is a change in API its considered a breaking change and would have to be targeted for OpenSearch 3.0. At the moment, OpenSearch 3.0 is the next planned release after OpenSearch 2.19.