Rest only High Level APIs completeness

[hub-cap]

There are a number of API that are exposed via REST but not via the Transport Client. They don't necessarily have to be implemented if the goal is feature parity with the Transport Client, yet we should probably have a look at why they were not added to the Transport Client and whether it makes sense to add their support to the high-level REST Client or not. I don't think it makes sense to add support for cat API and ingest processor grok, hence I took them out already.

• cluster remote info (@J-Bean)
• get source (@timoninmaxim)
• delete alias (@hub-cap)
  - [ ] get upgrade (@timoninmaxim)
• get grok patterns (GET /_ingest/processor/grok) (@jesinity)

taken from #27205

[elasticmachine]

Pinging @elastic/es-core-features (:Core/Features/Java High Level REST Client)

[qianyuxiang01]

Do you plan to complete those legacy RHLC api? @hub-cap

[har-vy]

Hi @hub-cap, I am a beginner, can I work on this?

[hub-cap]

@qianyuxiang01 I do not plan to personally complete these. I welcome community submissions.

@har-vy YES U CAN! :D Just pick one, maybe delete alias (the payload on the response is likely smaller so its easier to deal with). Feel free to post up a WIP and ask questions.

[deivids682]

Hi, @har-vy do you take a look? I can manage to do this one.

[har-vy]

@Deivids sure, I would probably have to pass this on.

[mohamadLy]

Hi, anyone on this right now. I was thinking picking it up if possible

[hub-cap]

I have done the delete alias. You can feel free to choose one of the API's and tell me so I can put your name next to it.