      // Query for existing chatter group records     List<CollaborationGroupMember> cGMember = [SELECT   Id,                                                          MemberId,                                                         CollaborationGroupId                                                FROM     CollaborationGroupMember                                                 WHERE    MemberId IN :userIds AND                                                          CollaborationGroupId IN :chatterGroups];      System.debug('member size is:: ' + cGMember.size());      