docs: @Override
      public IEntityGroup find(String key) throws GroupsException {
  
          if (isTreeRefreshRequired()) {
              refreshTree();
          }
  
          log.debug("Invoking find() for key:  {}", key);
  
          // All of our groups (incl. ROOT_GROUP)
          // are indexed in the 'groups' map by key...
          return groupsTree.getGroups().get(key);
      }