get:
  summary: Get user info
  parameters:
  - in: path
    name: user_id
    required: true
    schema:
      type: string
  - in: query
    name: fields
    schema:
      type: string
      default: all
  responses:
    '200':
      description: User info
      content:
        application/json:
          schema:
            $ref: '../schemas/User.yaml'
    '404':
      description: User not found
    '400':
      description: Request params are not correct
    '500':
      description: Unknown server error