Collection + json error response

gistfile1.txt

GET /foo?input=invalid HTTP/1.1
Host: example.com
Accept: application/vnd.collection+json,*/*

HTTP/1.1 400 Bad Request
Content-Type: application/vnd.collection+json

{
  "error": {
     "title": "Expected int in input",
     "code": "invalid_input_int",
     "message": "Input was 'invalid' expected an int"
  }
}