Swagger parser fails to link correct external reference if it refers to a file with non-unique name

[marcin-domanski-dis]

If we have a swagger file with references where only path is unique but filename is not, then swagger parser will mix responses resulting in a parser result not matching actual swagger definitions.

Example:
index.yaml with responses section like below:

paths:
  /entityA:
    get:
      responses:
        "200":
          $ref: ./responses/entityA/list.yaml
  /entityB:
    get:
      responses:
        "200":
          $ref: ./responses/entityB/list.yaml

Then both responses will be indexed with a same key resulting in only one of these is being used and other discarded.

This is because RefUtils.computeDefinitionName() will only use filename when computing external reference name

Tested with 2.1.22 and 2.1.24