docs: @Override
      public void removeChild(IGroupMember gm) throws GroupsException {
          String cacheKey = gm.getEntityIdentifier().getKey();
  
          if (getAddedMembers().containsKey(cacheKey)) {
              getAddedMembers().remove(cacheKey);
          } else {
              getRemovedMembers().put(cacheKey, gm);
          }
  
          primRemoveMember(gm);
      }