The following updates were made:
- Add a new untyped endpoint `{index}/_explain/{id}`.
- Add deprecation warnings to Rest*Action, plus tests in Rest*ActionTests.
- For each REST yml test, make sure there is one version without types, and another legacy version that retains types (called *_with_types.yml).
- Deprecate relevant methods on the Java HLRC requests/ responses.
- Update documentation (for both the REST API and Java HLRC).
* Deprecate types in count requests.
* Move RestCountAction to the 'search' package.
* Deprecate types in multi search requests.
* Add tests for types deprecation in the _search endpoint.
* Replace deprecated field `code` with `source` for stored scripts (#25127)
* Replace examples using the deprecated endpoint `{index}/{type}/_search`
with `{index}/_search` (#29468)
* Use a system property to avoid deprecation warnings after the Update
Scripts have been moved to their own context (#32096)
Adds docs for `HighLevelRestClient#multiSearch`. Unlike the `multiGet`
docs these are much more sparse because multi-search doesn't support
setting many options on the `MultiSearchRequest` and instead just wraps
a list of `SearchRequest`s.
Closes#28389