[elixir] Properly map AnyType

Created by: mrmstn

Fixes #14070 (closed)

This PR will handle AnyType as primitives to prevent the generator from generating specific classes, since in elixir structs cannot have any extra undefined files. This will also result in AnyType parameters not be serialized in any other way than Poison interprets it.

Since the Pet Store doesn't have some good examples to see the results of this change, here's a Dummy Spec:

openapi: 3.0.3
info:
  title: Dummy Spec
  version: 1.0.11
servers:
  - url: https://dummy.example.com/api
paths:
  /quotas:
    get:
      operationId: GetQuotas
      responses:
        "200":
          $ref: '#/components/responses/GetQuotasResponse'
      tags:
      - Enterprise
  /dummy:
    get:
      operationId: GetQuotas
      responses:
        "200":
          $ref: '#/components/responses/GetJobScaleStatusResponse'
      tags:
      - Enterprise
components:
  schemas:
    ConsulGateway:
      properties:
        Mesh: {}
      type: object
  responses:
    GetJobScaleStatusResponse:
      description: ""
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ConsulGateway'
    GetQuotasResponse:
      content:
        application/json:
          schema:
            items: {}
            type: array
      description: ""

The Spec contains two interesting parts. First, there is the ConsulGateway with the Mesh properties, with no further definition. Secondly, there is the GetQuotasResponse with an array of AnyType objects.

--- a/lib/nomad_client/api/enterprise.ex
+++ b/lib/nomad_client/api/enterprise.ex
@@ -21,7 +21,7 @@ defmodule NomadClient.Api.Enterprise do
   - `{:ok, [%AnyType{}, ...]}` on success
   - `{:error, Tesla.Env.t}` on failure
   """
-  @spec get_quotas(Tesla.Env.client, keyword()) :: {:ok, list(NomadClient.Model.AnyType.t)} | {:error, Tesla.Env.t}
+  @spec get_quotas(Tesla.Env.client, keyword()) :: {:ok, list(any())} | {:error, Tesla.Env.t}
   def get_quotas(connection, _opts \\ []) do
     request =
       %{}
@@ -32,7 +32,7 @@ defmodule NomadClient.Api.Enterprise do
     connection
     |> Connection.request(request)
     |> evaluate_response([
-      {200, [%NomadClient.Model.AnyType{}]}
+      {200, []}
     ])
   end

As you can see in the upper diff. The generator won't interpret the undefined list as %NomadClient.Model.AnyType{} anymore, but uses [] instead.

--- a/lib/nomad_client/model/consul_gateway.ex
+++ b/lib/nomad_client/model/consul_gateway.ex
@@ -12,15 +12,13 @@ defmodule NomadClient.Model.ConsulGateway do
   ]
 
   @type t :: %__MODULE__{
-    :Mesh => AnyType | nil
+    :Mesh => any() | nil
   }
 end
 
 defimpl Poison.Decoder, for: NomadClient.Model.ConsulGateway do
-  import NomadClient.Deserializer
-  def decode(value, options) do
+  def decode(value, _options) do
     value
-    |> deserialize(:Mesh, :struct, NomadClient.Model.AnyType, options)
   end
 end

In the upper diff, you can see that Mesh will not be decoded to the not existing NomadClient.Model.AnyType anymore. Mesh will not be serialized to a struct and will be left as is from Poison

@halostatue or @wing328 I would be honored if you could review my changes.

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