ModelBundle/Repository/ContentRepository.php
protected function generateContentTypeFilter($contentType)
    {
        $filter = null;

        if (!is_null($contentType) && '' != $contentType) {
            $filter = array('contentType' => $contentType);
        }

        return $filter;
    }
protected function generateContentTypeFilter($contentType)
    {
        $filter = null;

        if (!is_null($contentType) && '' != $contentType) {
            $filter = array('contentType' => $contentType);
        }

        return $filter;
    }
Generate Content Type filter

@param string|null $contentType

@return array|null