protected function resolveHelpMessageThumbnail($nodeTypeName, $configurationThumbnail)
    {
        if ($nodeTypeName !== null) {
            $thumbnailUrl = '';
            if (isset($configurationThumbnail)) {
                $thumbnailUrl = $configurationThumbnail;
                if (strpos($thumbnailUrl, 'resource://') === 0) {
                    $thumbnailUrl = $this->resourceManager->getPublicPackageResourceUriByPath($thumbnailUrl);
                }
            } else {
                # look in well know location
                $splitPrefix = $this->splitIdentifier($nodeTypeName);
                $relativePathAndFilename = 'NodeTypes/Thumbnails/' . $splitPrefix['id'] . '.png';
                $resourcePath = 'resource://' . $splitPrefix['packageKey'] . '/Public/' . $relativePathAndFilename;
                if (file_exists($resourcePath)) {
                    $thumbnailUrl = $this->resourceManager->getPublicPackageResourceUriByPath($resourcePath);
                }
            }
            return $thumbnailUrl;
        }
    }