private function discoverDataServices()
    {
        $path = $this->rootDir.'/'.$this->directory;
        $finder = new Finder();
        $finder->files()->in($path);

        /** @var SplFileInfo $file */
        foreach ($finder as $file) {
            $class = $this->classForFile($file);
            /* @var \Lullabot\Mpx\DataService\Annotation\DataService $annotation */
            $annotation = $this->annotationReader->getClassAnnotation(new \ReflectionClass($class), 'Lullabot\Mpx\DataService\Annotation\DataService');
            if (!$annotation) {
                continue;
            }

            // Now that we have a new data service, we need to attach any
            // custom field implementations.
            $customFields = $this->getCustomFields($annotation);
            $this->dataServices[$annotation->getService()][$annotation->getObjectType()][$annotation->getSchemaVersion()] = new DiscoveredDataService($class, $annotation, $customFields);
        }
    }