private function findPhpDocumentorPath()
    {
        $phpDocumentorPath = null;
        $directories = ['phpDocumentor', 'phpdocumentor'];
        foreach ($directories as $directory) {
            foreach (Phing::explodeIncludePath() as $path) {
                $testPhpDocumentorPath = $path . DIRECTORY_SEPARATOR . $directory . DIRECTORY_SEPARATOR . 'src';
                if (file_exists($testPhpDocumentorPath)) {
                    $phpDocumentorPath = $testPhpDocumentorPath;
                }
            }
        }

        return $phpDocumentorPath;
    }