Allows a listener to be notified when group membership changes. These callbacks are used in {@link org.jgroups.blocks.PullPushAdapter}.
The MembershipListener interface is similar to the {@link MessageListener} interface: every time a new view, a suspicion message, or a block event is received, the corresponding method of the class implementing MembershipListener will be called. Oftentimes the only method containing any functionality will be viewAccepted() which notifies the receiver that a new member has joined the group or that an existing member has left or crashed.