An abstract class implementing PortletMembershipListener.
Listeners can be configured for each portlet in sun-portlet.xml file.
Methods on these listeners are invoked everytime a member is added or removed in a
community, that is using this portlet. Framework initializes the listener instance with
the PortletContext in the init() method.
Called by framework when an instance is created. When overwritten, super.init(context) must
be called to initialize it correctly.
Parameters: pc - portlet context Parameters: sc - servlet context exception: com.sun.portal.portlet.service.provision.PortletMembershipException -