[HTML] Definition with array of definition objects does not generate property

Description

When creating a definition which is an array whose items are another definition, the generated static HTML file lists nothing under the array-typed definition.

Swagger-codegen version

2.2.1

Swagger declaration file content or url

swagger: '2.0'
definitions:
  Foo:
    type: array
    items:
      $ref: '#/definitions/Bar'
  Bar:
    type: object
    properties:
      blah:
        type: string

Command line used for generation

java -jar swagger-codegen-cli.jar generate -i swagger.yaml -l html

Steps to reproduce

• Have a definition which is an array whose items are a $ref to another definition
• Generate static HTML docs with -l html
• Observe generated index.html contains an empty definition for the array-typed definition (Foo, in the above example)

Related issues/PRs

Possibly related to #6974

Suggest a fix/enhancement

Reproduce the issue with the supplied swagger.yaml definition and java -jar swagger-codegen-cli.jar generate -i swagger.yaml -l html, then inspect the generated index.html for Foo. Trace the HTML generator entry point and related templates or tests for array definitions. Done means Foo displays its referenced Bar properties instead of an empty definition.