Responses using ref aren't supported

[JohnRoux]

Currently only schema references are supported.
I think we need to do a couple checks here as several swagger objects should be supported.

My use-case for this is pretty simple. Api has a couple of generic responses (404, 401 etc), duplicating all of those for each request isn't ideal, and the perfect usecase for using a ref.

This is where the issue is actually breaking
AbstractBody Line 331:

 if(!isset($schemaArray['$ref']) && isset($schemaArray['content'])) {
            $schemaArray['$ref'] = $schemaArray['content'][key($schemaArray['content'])]['schema']['$ref'];
        }

Api Doc Example:

"/api/user": {
            "get": {
                "tags": [
                    "User"
                ],
                "summary": "Get list of all users",
                "description": "Returns list of users",
                "operationId": "user_index",
                "parameters": [
                    {
                        "$ref": "#/components/parameters/UserIncludes"
                    }
                ],
                "responses": {
                    "200": {
                        "description": "User Collection",
                        "content": {
                            "application/json": {
                                "schema": {
                                    "$ref": "#/components/schemas/User"
                                }
                            }
                        }
                    },
                    "401": {
                        "$ref": "#/components/responses/Unauthorized"
                    },
                    "404": {
                        "$ref": "#/components/responses/ModelNotFound"
                    }
                },
                "security": [
                    {
                        "apiAuth": []
                    }
                ]
            }
        },