code: @Path("userGroups")
      public DirectoryResource<UserGroup, APIUserGroup> getUserGroupDirectoryResource()
              throws GuacamoleException {
          return userGroupDirectoryResourceFactory.create(userContext,
                  userContext.getUserGroupDirectory());
      }
docs: Returns a new resource which represents the UserGroup Directory contained
  within the UserContext exposed by this UserContextResource.
  
  @return
  A new resource which represents the UserGroup Directory contained
  within the UserContext exposed by this UserContextResource.
  
  @throws GuacamoleException
  If an error occurs while retrieving the UserGroup Directory.