xml:attribute on a response property defined inline improperly renders as an element in the XML example output

Description

When defining a response property inline with the xml:attribute value set to true, the XML example output improperly renders the property as an element instead of an attribute. Note that when the response property is defined in the "definitions" section, the xml:attribute value works as expected and renders the item properly as an attribute.

Swagger-codegen version

master

Swagger declaration file content or url

swagger: '2.0'
info:
  title: 'inline xml:attribute issue'
  version: '1'
  
definitions:
  'response':
    type: object
    xml:
      name: 'test'
    properties:
      'attribute':
        type: string
        example: 'value'
        xml:
          attribute: true
      'element':
        type: string
        example: 'value'

paths:
  '/defined-response':
    get:
      produces: [ 'application/xml' ]
      responses:
        200:
          description: Success
          schema:
            $ref: '#/definitions/response'
  '/inline-response':
    get:
      produces: [ 'application/xml' ]
      responses:
        200:
          description: Success
          schema:
            type: object
            xml:
              name: 'test'
            properties:
              'attribute':
                type: string
                example: 'value'
                xml:
                  attribute: true
              'element':
                type: string
                example: 'value'

Command line used for generation

Generate any docs that show the XML example output.

Steps to reproduce

Generate any docs that show the XML example output and the output for two paths in the example will be:

/defined-response - works - The "attribute" property is properly rendered as an attribute of the parent:

<test attribute="value">
  <element>value</element>
</test>

/inline-response - does not work - The "attribute" property is incorrectly rendered as an element of the parent:

<test>
  <attribute>value</attribute>
  <element>value</element>
</test>

Use the Swagger declaration in the issue as the reproduction input and generate documentation containing XML example output for both response definitions. Compare the defined-response and inline-response cases; done means the inline response renders attribute="value" on , matching the referenced definition, with a regression check for both outputs.