{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "title": "Combining at top level",
  "description": "For the combine",
  "type": "object",
  "oneOf": [
    { "$ref": "#/definitions/diskDevice" },
    { "$ref": "#/definitions/diskUUID" },
    { "$ref": "#/definitions/nfs" },
    { "$ref": "#/definitions/tmpfs" }
  ],
  "definitions": {
    "diskDevice": {},
    "diskUUID": {},
    "nfs": {},
    "tmpfs": {}
  }
}