Vaadin Collaboration Engine 3.2.0.alpha2

Add PresenceManager API to handle user presence in topics

The new PresenceManager can now be used as a middle-layer API to handle user presence in topics: set the local-user presence, handle user presence changes and get the present users in a topic. This new API makes it easy to create custom components with collaboration features, for example a list of active users:

VerticalLayout users = new VerticalLayout();
PresenceManager presence = new PresenceManager(users, ownUserInfo, topicId);
presence.setAutoPresence(true);
presence.setNewUserHandler(newUserInfo -> {
   Component card = createUserCard(newUserInfo);
   users.add(card);
   return () -> users.remove(card);
});

Related issue: #37

Other changes

• Fixed URL authorization issues with Spring Security (#41)
• Push is now automatically enabled (#43)