[ALL] [3.0] No description for parameters in form-data request bodies

Description

I'm switching from Swagger to OpenAPI and noticed that Codegen no longer generates descriptions for parameters of "form-data" request bodies. This used to work (and should be working if I interpret the spec correctly).

Swagger-codegen version

I'm using version 3.0.4. It's a regression to Swagger (i.e. v2).

Swagger declaration file content or url

openapi: 3.0.0
info:
  title: Test Api
  version: '1.0.0'

paths:
  "/pet":
    post:
      summary: Updates a pet in the store with form data
      operationId: updatePetWithForm
      requestBody:
        description: pet update data
        content:
          application/x-www-form-urlencoded:
            schema:
              type: object
              properties:
                name:
                  description: Updated name of the pet
                  type: string
                status:
                  description: Updated status of the pet
                  type: string
      responses:
        "405":
          description: Invalid input

Command line used for generation

java -jar swagger-codegen-cli-3.0.4.jar generate --input-spec test.openapi.yaml --lang java --output generated

Steps to reproduce

1. Generate code with information above
2. Inspect file generated/src/main/java/io/swagger/client/api/DefaultApi.java

Notice that the generated documentation for updatePetWithForm() is like this:

/**
 * Updates a pet in the store with form data
 * 
 * @param name  (optional)
 * @param status  (optional)
 * @throws ApiException If fail to call the API, e.g. server error or cannot deserialize the response body
 */

Notice how no description is inserted for name or status.

Related issues/PRs

I found no related issues.

Suggest a fix/enhancement

The problem is "introduced" in DefaultCodegenConfig.fromOperation(). There is a block that handles request bodies with mime types application/x-www-form-urlencoded and multipart/form-data. In that block the CodegenParameter instances are created like this:

CodegenParameter formParameter = fromParameter(new Parameter()
		.name(propertyName)
		.schema(propertyMap.get(propertyName)), imports);

The problem now is that the description is (only) in the schema - but neither Parameter.schema() nor Parameter.getDescription() "transfer" the description from the schema.

Thus, when the CodegenParameter is created by DefaultCodegenConfig.fromParameter(), this code "generates" an empty description:

codegenParameter.description = escapeText(parameter.getDescription());

The problem could be solved in all of these 4 places - but I have no idea what would be the best place (although I think the last option would be the "worst"):

1. DefaultCodegenConfig.fromOperation()
2. Parameter.schema()
3. Parameter.getDescription()
4. DefaultCodegenConfig.fromParameter()

Start in DefaultCodegenConfig.fromOperation(), where form-data CodegenParameter instances are created, then trace DefaultCodegenConfig.fromParameter() and the schema description handling. Re-run the shown Java generation command and inspect generated/src/main/java/io/swagger/client/api/DefaultApi.java; done means the generated updatePetWithForm() documentation includes descriptions for name and status.