public function mergeCollectionConfig(array $config)
    {
        if ($this->collectionConfig === null) {
            $this->setCollectionConfig($config);

            return $this;
        }

        $this->collectionConfig = array_replace_recursive(
            $this->defaultCollectionConfig(),
            $this->collectionConfig,
            $this->parseCollectionConfig($config)
        );

        return $this;
    }