code: @Override
  	public <T extends Resource> T resourceById(ResourceId id, Class<? extends T> expectedResourceClass) {
  		checkNotNull(expectedResourceClass,"Expected resource class cannot be null");
  		Resource found=find(id);
  		if(expectedResourceClass.isInstance(found)) {
  			return expectedResourceClass.cast(found);
  		}
  		return null;
  	}
docs: {@inheritDoc}