public static function getDataSources($objectManager)
    {
        $reflectionService = $objectManager->get(ReflectionService::class);

        $dataSources = [];
        $dataSourceClassNames = $reflectionService->getAllImplementationClassNamesForInterface(DataSourceInterface::class);
        /** @var $dataSourceClassName DataSourceInterface */
        foreach ($dataSourceClassNames as $dataSourceClassName) {
            $identifier = $dataSourceClassName::getIdentifier();
            if (isset($dataSources[$identifier])) {
                throw new NeosException(sprintf('Data source with identifier "%s" is already defined in class %s.', $identifier, $dataSourceClassName), 1414088185);
            }
            $dataSources[$identifier] = $dataSourceClassName;
        }

        return $dataSources;
    }