LID of whoever performed the action (<notification participant>).
Phone-number JID of whoever performed the action (<notification participant_pn>).
Username of whoever performed the action, when the server sends one.
True when the notification carries no <participant> child, i.e. the action targets the actor.
LID of the participant the action targets. undefined when the server addressed the
target by phone number and sent no lid attribute — it is never borrowed from the actor.
Phone-number JID of the participant the action targets. undefined when the server
addressed the target by LID and sent no phone_number attribute.
The acting + affected participants of a
w:gp2group notification.