public function getFileContents()
        {
            if ($this->fileContentsCache === null && $filePath = $this->getFile()) {

                // Return null if the file doesn't actually exist - this may
                // happen in cases where the filename is provided as, for
                // example, 'Unknown'
                if (!File::exists($filePath)) {
                    return null;
                }

                $this->fileContentsCache = File::read($filePath);
            }

            return $this->fileContentsCache;
        }