/**
* Returns a list of people that correspond to the passed in person ids.
*
* @param userIds A set of users
* @param groupId The group
* @param collectionOptions How to filter, sort and paginate the collection being fetched
* @param fields The profile details to fetch. Empty set implies all
* @param token The gadget token @return a list of people.
*/
abstract public RestfulCollection<Person> getPeople(HashSet<UserId> userIds, GroupId groupId,
CollectionOptions collectionOptions, HashSet<String> fields, ISecurityToken token);