protected function _createManager(array $definitions)
    {
        $manager = new DefinitionManager();

        foreach ($definitions as $name => $definition)
        {
            if ($definition instanceof DefinitionHelperInterface) {
                /** @var DefinitionHelperInterface $definition */
                $manager->add($definition->getDefinition($name));
            } else if ($definition instanceof EntryReference) {
                /** @var EntryReference $definition */
                $manager->add(new AliasDefinition($name, $definition->getName()));
            } else {
                $manager->add(new ValueDefinition($name, $definition));
            }
        }
        return $manager;
    }