Making a general swagger parameter definition more specific, by adding json-schema information.

part of a json-schema otherfile.json

...
"definitions": {
  "special_id_csv": {
		"description": "One or more of a particular kind of id separated by comma \",\"",
		"type": "string",
		"pattern": "^...regrexregexregexregexregex...$"
	},
}
...

parts of swagger.json

"parameters": {
  ...
		"filter[id]": {
			"name": "filter[id]",
			"description": "If specified, return only records matching that id or ids. May be one or more valid ids, separated by comma \",\".",
			"in": "query",
			"type": "string"
		},
	...
}
...inside a partcular path/operation/parameters: [
  ...
  { "allOf": [
      {"$ref": "#/parameters/filter[id]"},
      {"$ref": "otherfile.json#/definitions/special_id_csv"}
  ] },
  ...
]