{
  "$schema": "http://json-schema.org/schema#", 
  "type": "object", 
  "description": "ExternalDocumentation allows referencing an external resource for extended documentation.", 
  "properties": {
    "url": {
      "type": [
        "string", 
        "null"
      ]
    }, 
    "description": {
      "type": [
        "string", 
        "null"
      ]
    }
  }
}