Elixir Generator generates code with lots of warnings

Created by: halostatue

Description

When compiling Elixir code generated with openapi-generator, there are compiler warnings (this is using ory/sdk/clients/client/elixir:

$ mix deps.get
warning: use Mix.Config is deprecated. Use the Config module instead
  config/config.exs:3

Resolving Hex dependencies...
Dependency resolution completed:
Unchanged:
  mime 2.0.2
  poison 3.1.0
  tesla 1.4.4
* Getting tesla (Hex package)
* Getting poison (Hex package)
* Getting mime (Hex package)

There are other warnings:

$ mix compile
…
warning: found quoted atom "namespace" but the quotes are not required. Atoms made exclusively of ASCII letters, numbers, underscores, and optionally ending with ! or ? do not require quotes
  lib/ory/api/read.ex:38:7
…

The code in question for the latter (and there are hundreds of these) is

    optional_params = %{
      :"namespace" => :query,
      :"object" => :query,
      :"relation" => :query,
      :"subject_id" => :query,
      :"subject_set.namespace" => :query,
      :"subject_set.object" => :query,
      :"subject_set.relation" => :query,
      :"max-depth" => :query
    }

It should be

    optional_params = %{
      :namespace => :query,
      :object => :query,
      :relation => :query,
      :subject_id => :query,
      :"subject_set.namespace" => :query,
      :"subject_set.object" => :query,
      :"subject_set.relation" => :query,
      :"max-depth" => :query
    }

The atom issue can be changed to the correct format by the use of mix format in the target directory, but that requires a .formatter.exs be created (which should be in every Elixir project at this point):

[
  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
]

I will be opening at least one issue in the generated repo for some issues that I have seen, but for what I have highlighted here, these are issues in the Elixir generator or its templates (I reviewed the templates before opening this issue).

I’m happy to provide a PR, but I haven’t seriously done Java since JDK 1.1.

Related issues/PRs

#12484 (closed)
#4011
#10755 (I will have to investigate, but this can probably be resolved by making sure references to the self module are changed to __MODULE__)
#8804 (Jason is generally the preferred JSON parser/encoder in Elixir these days in any case)
#12268 (this should be using Application.compile_env/2 instead of Application.get_env/2, or using a code fallback)