code: public static List<String> getSharedGroups(XMPPConnection connection) throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException {
          // Discover the shared groups of the logged user
          SharedGroupsInfo info = new SharedGroupsInfo();
          info.setType(IQ.Type.get);
  
          SharedGroupsInfo result = connection.createStanzaCollectorAndSend(info).nextResultOrThrow();
          return result.getGroups();
      }
docs: Returns the collection that will contain the name of the shared groups where the user
  logged in with the specified session belongs.
  
  @param connection connection to use to get the user's shared groups.
  @return collection with the shared groups' name of the logged user.
  @throws XMPPErrorException
  @throws NoResponseException
  @throws NotConnectedException
  @throws InterruptedException