Use params modifier for methods in RequestDescriptorBase

[tkirill]

Hello!

This PR tries to fix #4471.

The only place I found to fix is RequestDescriptorBase.FilterPath so either this is a really low hanging fruit or I'm completely missing something. I searched for potential places to fix with naive search for (string[] and with looking at usings of TypeHighLevel in views.

I noticed that methods in Descriptors.*.cs already have params modifier and then found that it is implemented with .DescriptorArgumentType in Descriptor.cshtml. Looks like it is suitable for RequestDescriptorBase too.

I'm not sure if Descriptors.cs should be commited. The whole process of testing codegen is a little bit confusing and I didn't figured out the right way to run tests locally for my changes (and will be glad if someone teach me). Anyway it was a very interesting exercise to look through the code generation tool.

[Mpdreamz]

Thanks @tkirill for taking on this challenge!

Also your input into the documentation of this process is invaluable we'll work on improving our Contributing.md 👍

This is not a breaking change as per: https://docs.microsoft.com/en-us/dotnet/core/compatibility/#code-changes so LGTM.

I do think wherever we accept params we should create a non allocating overload with IEnumerable too. Are you up for the challenge to update this PR? If not no sweat we'll amend afterwards.

[tkirill]

@Mpdreamz Yes, sure I want, this is very interesting challenge. At least I'll try.

I guess I don't fully understand the scope of the task. This is how I see it:

• For each API endpoint there are two parts: low-level (RequestParameters.*.cs, ElasticLowLevelClient.*.cs) in Elasticsearch.Net and high-level in Nest. This task is about high-level code.
• High-level code can be auto-generated (Descriptors.*.cs, Requests.*.cs, ElasticClient.*.cs) and manual-writed. Manual-writed descriptors always have both IEnumerable and params overloads. Auto-generated descriptors have only params version and we want to add IEnumerable overload.
• So the targets are Descriptor.cshtml and RequestDescriptorBase.cshtml

If this is far from being the whole story then I guess it will take unreasonably much of your time to explain me what to do. In this case I'll be happy to stop on current tiny contribution and just wait and look at full solution later. And if everything is actually fine then I can do it and it will be very interesting.

[Mpdreamz]

Hey @tkirill your suggested scope is the whole nine yards :)

I was talking about simply extending this PR so that ``src/Nest/Descriptors.cs also includes the overload. Keeps the PR small and manageable 👍

[tkirill]

Hey @Mpdreamz I added IEnumerable overload.

[codebrain]

This is great @tkirill! thank you for your contribution.
I will get this merged in and ready for 7.7.0.

[codebrain]

Backported to 7.x and 7.7