Referenced schemas in callback responses are not resolved [Regression in 2.1.19]

Input
Given the following OpenAPI specs:

openapi.yaml

openapi: 3.0.2
info:
  title: But
  version: 1.0.0
paths:
    '/resource':
      $ref: operation.yaml#/paths/~1resource

operation.yaml

openapi: 3.0.2
info:
  title: But
  version: 1.0.0
paths:
  '/resource':
    get:
      operationId: Operation
      responses:
        '200':
          description: Operation was Successfull and the below response structure is returned
      callbacks:
        SomeCallback:
          '/callback':
            get:
              responses:
                '200':
                  description: Success
                  content:
                    application/json:
                      schema:
                        $ref: '#/components/schemas/Response'
components:
  schemas:
    Response:
      type: object
      properties:
        name:
          type: string

parsing with

var options = new ParseOptions();
options.setResolve(true);
var result = new OpenAPIParser().readLocation("openapi.yaml", null, options);

Expected result:
The result contains the Response schema in components.schemas.

Observed result:
The Response schema is missing. This worked as expected until including 2.1.18 and is broken afterwards.

Reproduce the issue with openapi.yaml and operation.yaml using ParseOptions.setResolve(true) and OpenAPIParser.readLocation. Compare behavior between versions 2.1.18 and 2.1.19, then trace resolution of the callback response's schema reference. Done means the resolved result contains components.schemas.Response as in the expected result.