code: @SuppressWarnings("unchecked")
  	public <T> T get(Descriptor<T> descriptor) {
  		if (context == null) {
  			return super.get(descriptor);
  		}
  		
  		Map<Descriptor<?>, Object> components 
  				= (Map<Descriptor<?>, Object>) context.getAttribute(COMPONENTS);
  		return (T) components.get(descriptor);
  	}
docs: Returns the component corresponding to the specified {@link Descriptor}
  from the current {@code ServletContext}.
  If the application is not running in Web environment, the component is
  got from {@code SingletonContext}'s component store.
  
  @param <T> The component type.
  @param descriptor The descriptor corresponding to the component.
  @return The component corresponding to the specified {@link Descriptor}.