docs: private static MultiUserChat getMuc(XMPPConnection connection, Jid jid) {
          EntityBareJid ebj = jid.asEntityBareJidIfPossible();
          if (ebj == null) {
              return null;
          }
  
          MultiUserChatManager mucm = MultiUserChatManager.getInstanceFor(connection);
          Set<EntityBareJid> joinedRooms = mucm.getJoinedRooms();
          if (joinedRooms.contains(ebj)) {
              return mucm.getMultiUserChat(ebj);
          }
  
          return null;
      }