code: @Path("{identifier}")
      public DirectoryObjectResource<InternalType, ExternalType>
          getObjectResource(@PathParam("identifier") String identifier)
              throws GuacamoleException {
  
          // Retrieve the object having the given identifier
          InternalType object = directory.get(identifier);
          if (object == null)
              throw new GuacamoleResourceNotFoundException("Not found: \"" + identifier + "\"");
  
          // Return a resource which provides access to the retrieved object
          return resourceFactory.create(userContext, directory, object);
  
      }
docs: Retrieves an individual object, returning a DirectoryObjectResource
  implementation which exposes operations available on that object.
  
  @param identifier
  The identifier of the object to retrieve.
  
  @return
  A DirectoryObjectResource exposing operations available on the
  object having the given identifier.
  
  @throws GuacamoleException
  If an error occurs while retrieving the object.