IRCEvent to filter.
The Permissions context in which this user should be filtered.
Whether to rely on hostmasks for user identification, or to use services account logins, which need to be issued WHOIS queries to divine.
A FilterResult saying the event should pass, fail, or that more information about the sender is needed via a WHOIS call.
Decides if a sender meets a Permissions and is allowed to trigger an event handler, or if a WHOIS query is needed to be able to tell.
This requires the Persistence service to be active to work.