openapi: 3.0.0
info:
  title: My API
  version: '0.1'
paths:
  /books/{bookId}:
    get:
      parameters:
        - in: header
          name: bookId
          description: book ID
          schema:
            type: object
            properties:
              name:
                type: string
                enum:
                  - VALUE_1
                  - VALUE_2
                  - VALUE_3  
      responses:
        '200':
          description: successfully retrieved book details