* @type string|array $role An array or a comma-separated list of role names that users must match
* to be included in results. Note that this is an inclusive list: users
* must match *each* role. Default empty.
* @type string|array $role An array or a comma-separated list of role names that users must match
* to be included in results. Note that this is an inclusive list: users
* must match *each* role. Default empty.