My lambda api redirects url to another url. To document this on swagger UI. It gives CORS Error. this works fine with postman or from browser

Error message

TypeError: cross-origin to google.com denied by CORS policy. Origini null not allowd by Access-contrl-allow-origin

Note : I am using open api version version 2:0

my endpoint : https://my-domain/123456 -> redirects to google.com

serverless.yml

event:
 -http:
  path: / 
  method: ANY
  cors:true

app.js

 app.use(cors())

my swagger.yml

/{shortUrl}:
    get:
      tags:
        - 'Redirection'
      summary: 'Redirect short URL -> Original'
      description: 'This route redirects user to original URL website when a get is sent to trimified URL'
      produces:
        - 'text/plain; charset=utf-8'
      parameters:
        - name: 'shortUrl'
          in: 'path'
          description: 'ID of short URL'
          required: true
          type: 'string'
      responses:
        '400':
          description: 'Invalid URL'
          schema:
            $ref: '#/responseDefinitions/UserErrorResponse'
        '201':
          description: 'OK'
          schema:
            $ref: '#/responseDefinitions/ApiResponse'
        '500':
          description: 'Internal Server Error'
          schema:
            $ref: '#/responseDefinitions/ServerErrorResponse'