public function warm()
    {
        $warmed = [];
        if (false === $this->mf->hasCache()) {
            return $warmed;
        }

        $this->clear();
        foreach ($this->mf->getAllTypeNames() as $type) {
            $metadata = $this->mf->getMetadataForType($type);
            $warmed[] = $type;
        }
        return $warmed;
    }