OpenAPI spec with multipart file upload

openapi-multipart.yaml

openapi: 3.0.3
info:
  version: "1.0.0"
  title: "Multipart file upload"
paths:
  /files:
    post:
      summary: Upload files
      operationId: uploadFiles
      requestBody:
        required: true
        content:
          multipart/form-data:
            schema:
              $ref: '#/components/schemas/ReceiptUpload'
      responses:
        201:
          description: OK
components:
  schemas:
    ReceiptUpload:
      type: object
      properties:
        nonfileProperty:
          description: 'The PartnerNumber of the person this receipt references to'
          type: string
        file:
          description: 'The documents to upload. Specify this parameter multiple times for multiple documents.'
          type: array
          items:
            type: string
            format: binary
      required:
        - nonfileProperty
        - file