x-apigateway-backend.functionEndpoints

含义：API网关定义的FUNCTION类型API后端服务定义。

作用域：x-apigateway-backend

示例：

paths:
  '/users/{userId}':
    get:
      produces:
        - "application/json"
      parameters:
        - name: "X-Auth-Token"
          description: "认证token"
          type: "string"
          in: "header"
          required: true
      responses:
        default:
          description: "default response"
      x-apigateway-request-type: "public"
      x-apigateway-backend:
        type: "FUNCTION"
        functionEndpoints:
          version: "v1"
          function-urn: ""
          invocation-type: "synchronous"
          timeout: 30000