Uppercase property names lead to java code that produces wrong json.

Description

If the swagger declaration contains properties with names containing only uppercase letters and underscores, the generated java code is not java bean conform. As a result jackson maps the properties twice. This actually is part of #4051 but the code currently handles this case earlier.

Swagger-codegen version

Tested with 2.2.1 and 2.2.2-SNAPSHOT

Swagger declaration file content or url

swagger: '2.0'
schemes:
  - http
basePath: '/v0.1/foo'
consumes:
  - 'application/json'
produces:
  - 'application/json'
paths:            
  '/foo':
    get:
      responses:
        200:
          description: "successful operation"
          schema:
            type: "array"
            items:
              $ref: "#/definitions/Pet"

definitions:

  Pet:
    description: >
      Pet
    type: object
    properties:
      ATT_NAME:
        description: >
          Name of the pet
        type: string

Command line used for generation

swagger-codegen-maven-plugin

Steps to reproduce

Build a jaxrs or spring server. Implement controller to return Pet array.
Or use jackson mapper and serialize with the generated Pet model code.

Related issues

https://github.com/swagger-api/swagger-codegen/issues/4051

Suggest a Fix

AbstractJavaCodegen

    @Override
    public String toVarName(String name) {
        // sanitize name
        name = sanitizeName(name); // FIXME: a parameter should not be assigned. Also declare the methods parameters as 'final'.

        if ("class".equals(name.toLowerCase())) {
            return "propertyClass";
        }

        if("_".equals(name)) {
          name = "_u";
        }

        // if it's all uppper case, do nothing
//        if (name.matches("^[A-Z_]*$")) {
//            return name;
//        }

        // camelize (lower first character) the variable name
        // pet_id => petId
        name = camelize(name, true);

        // for reserved word or word starting with number, append _
        if (isReservedWord(name) || name.matches("^\\d.*")) {
            name = escapeReservedWord(name);
        }

        return name;
    }

Start in AbstractJavaCodegen.toVarName, using the supplied ATT_NAME Swagger declaration and the generated Pet model as the reproduction case. Run generation through the swagger-codegen-maven-plugin, then serialize the generated model with Jackson. Done means the uppercase property is Java-bean conform and is mapped only once in the resulting JSON.