Swagger multiple Schemas in one response

openapi: 3.0.0
info:
  version: '1.0'
  title: Receipt API
  description: the ultimate receipt API
servers:
  # Added by API Auto Mocking Plugin
  - description: SwaggerHub API Auto Mocking
    url: https://virtserver.swaggerhub.com/d.martins/receipts/1.0
    
paths: 
  /receipts/:
    post: 
      tags:
      - Receipts
      requestBody:
          $ref: '#/components/requestBodies/Items'
      responses:
        201:
          description: Created
          
          
components:
  requestBodies:
    Items:
      content:
        'application/json':
          schema:
            $ref: '#/components/schemas/Items'
    Merchant:
      content:
        'application/json':
          schema:
            $ref: '#/components/schemas/Merchant'

  schemas:
      Items: 
        type: object
        properties:
            product:
              type: integer
              example: Bananas 
            product category:
              type: integer
              example: Healthy fruit 
            ean:
              type: string
              example: 1234567891012
            price:
              type: number
              example: 19,99€
            discount:
              type: string
              example: 15%
            discount value: 
              type: number
              example: 2,98€
      Merchant:
        type: object
        properties:
          merchant id: 
            type: number
            example: 12345
          store id:
            type: string
            example: ABC123456789
          cashier:
            type: string
            example: Max Muster
            
      Receipt_properties:
        type: object
        properties:
          Receipt id:
            type: string
            example: ABC123456789123456789
          transaction date and time: 
            type: string
            example: 2021-05-05T11:11:11.123Z
            format: date-time
            
        

Hey everyone,

i am new to coding and try to learn how to create an api by writing one that should transfer receipt data.

i managed to create Schemas to have a nice overview of all values.

However i only manage to get one schema into my Post response, whatever i try i just run into error which is quite frustrating. 

I am Happy for any help!

attached is the code: