Who said you can't include an entity body with a 422 status? e.g.: HTTP/1.1 422 Unprocessable Entity {"error": "email address must contain @", "applies_to": "

Who said you can't include an entity body with a 422 status? e.g.: HTTP/1.1 422 Unprocessable Entity {"error": "email address must contain @", "applies_to": "email_field"}