public function getObjectDescriptor($name)
    {

        // query if we've an object descriptor registered
        if ($this->hasObjectDescriptor($name)) {
            // return the object descriptor
            return $this->objectDescriptors->get($name);
        }

        // throw an exception is object descriptor has not been registered
        throw new UnknownObjectDescriptorException(sprintf('Object Descriptor with name "%s" has not been registered', $name));
    }