Returns a dictionary of rosters, where the key is the name of the roster, and the value is an array list of string user names.
This function was designed to run in the Gateway and in Perspective sessions. If creating rosters from Vision clients, use system.alarm.getRosters instead.
Dictionary - A dictionary that maps roster names to a List of usernames in the roster. The List of usernames may be empty if no users have been added to the roster.
Gateway, Perspective Session
system roster getRosters, roster.getRosters