[Go] Add multiple servers support to Go(-experimental) client

[jirikuncar]

Allows the Go(-Experimental) API client to retrieve all server URLs defined in the spec

PR checklist

• Read the contribution guidelines.
• If contributing template-only or documentation-only changes which will change sample output, build the project before.
• Run the shell script(s) under ./bin/ (or Windows batch scripts under.\bin\windows) to update Petstore samples related to your fix. This is important, as CI jobs will verify all generator outputs of your HEAD commit, and these must match the expectations made by your contribution. You only need to run ./bin/{LANG}-petstore.sh, ./bin/openapi3/{LANG}-petstore.sh if updating the code or mustache templates for a language ({LANG}) (e.g. php, ruby, python, etc).
• File the PR against the correct branch: master, 4.3.x, 5.0.x. Default: master.
• Copy the technical committee to review the pull request if your PR is targeting a particular programming language.

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cc @antihax (2017/11) @bvwells (2017/12) @grokify (2018/07) @kemokemo (2018/09) @bkabrda (2019/07)

related PRs

• Add multiple servers support to PHP client #1964
• Add multiple servers support to Python client #1969
• Add "servers" support to Ruby API client #1280

[bkabrda]

Great stuff. There are couple minor things that I'd suggest fixing (see the review), but otherwise this is great start to support server variables.
Additionally, this is in line with what other languages (e.g. Python) use, so this is also ok in terms of consistency across the whole project.

[bkabrda]

@wing328 hey William 👋 . It seems that this PR is failing in CI because it uses Go 1.12 (released February 2019) feature (strings.ReplaceAll). Is there any documentation available on which go releases we want to support?

Otherwise this PR LGTM, so once we clear the situation with strings.ReplaceAll I will give it a 👍 .

[bkabrda]

Ah, please disregard my previous comment, I was looking wrong. This now uses strings.Replace, it just needs to have the samples regenerated after moving to this.

[jirikuncar]

Run the shell script(s) under ./bin/ (or Windows batch scripts under.\bin\windows) to update Petstore samples related to your fix. This is important, as CI jobs will verify all generator outputs of your HEAD commit, and these must match the expectations made by your contribution. You only need to run ./bin/{LANG}-petstore.sh, ./bin/openapi3/{LANG}-petstore.sh if updating the code or mustache templates for a language ({LANG}) (e.g. php, ruby, python, etc).

@bkabrda it seems that the PR description template is not completely acurate.

$ find . -iname \*go-\*.sh | grep -v server
./bin/go-experimental-petstore.sh
./bin/openapi3/go-experimental-petstore.sh
./bin/openapi3/go-petstore.sh
./bin/go-petstore-withxml.sh # <- I was missing this one !!!
./bin/go-petstore.sh

I wish there was a Makefile and/or pre-commit hook for this that would check which samples need to be regenerated based on list of edited files.

$ make samples
# or
$ make samples-go samples-go-experimental

[bkabrda]

Perfect, LGTM now 👍

[jirikuncar]

@antihax (2017/11) @bvwells (2017/12) @grokify (2018/07) @kemokemo (2018/09) @bkabrda (2019/07) I have rebased the PR and regenerated the client code.