[HTML2] Undefined response schema when is of type array

Description

API documentation generated used HTML2 language gives 'undefined' schema when it's of type array. To see the schema you need to wind and unwind it, as shown on photos.

Swagger-codegen version

2.3.1

Swagger declaration file content or url

     responses:
        200:
          description: "Some description"
          schema:
            type: "array"
            items:
              $ref: "#/definitions/SomeDefinition"

Command line used for generation

java -jar webservice/docs/swagger-codegen-cli.jar generate \
    -i webservice/swagger/swagger.yaml \
    -l html2 \
    -o webservice/docs/API_docs

Steps to reproduce

Related issues/PRs

Suggest a fix/enhancement

I have 3 responses of array type and each one has this problem, returning response as object works fine, so I'm sure it's because of the array response

Start by reproducing the issue with the provided Swagger schema and the swagger-codegen CLI command using the html2 generator. Inspect the generated API documentation and the HTML2 generation path for array response schemas. Done means array responses display their referenced schema immediately, without needing to collapse and expand the response.