Mule 4 - Return error if passing payload request parameter that was not defined in the raml

Question

just to check is it possible to return an error if the user passed the parameter that was not defined in the api raml? For eg, below is my defined body payload structure in my api raml

{
  "test1": "value1",
  "test2": "value2",
  "test3": "value3"
}

and I would like to return error if the user passed any parameter that was not defined in the body payload structure above, for eg

{
  "test1": "value1",
  "test2": "value2",
  "test3": "value3",
  "4": "5"
}

Sample of RAML for discussion

#%RAML 1.0
title: Sample API
version: 1.0
/users:
    description: This is sample only
    post:
      body: 
        application/json:
          example: |
            {
           "test1": "value1",
           "test2": "value2",
           "test3": "value3"
            } 
      responses: 
        200:
          body: 
            application/json:
              example: |
                {
                "message":"This is for testing purposes"
                }

Answer 1

First you need to define the type for the body. A JSON schema may also work. An example is not an schema nor it will be used to validate inputs. Although in modern versions of MuleSoft products the example will be validated. I use the additionalProperties: false configuration for the type so the validation rejects extra attributes.

Example:

#%RAML 1.0
title: Sample API
version: 1.0

types:
  test_type:
    additionalProperties: false
    type: object
    properties:
      test1:
        type: string
        required: true
      test2:
        type: string
        required: true
      test3:
        type: string
        required: true

/users:
    description: This is sample only
    post:
      body: 
        application/json:
          type: test_type
          example: |
            {
              "test1": "value1",
              "test2": "value2",
              "test3": "value3"
            } 
      responses: 
        200:
          body: 
            application/json:
              example: |
                {
                "message":"This is for testing purposes"
                }