public URL adjustJarFileEntryUrl(URL url, URL rootUrl) {
		final String protocol = url.getProtocol();
		final boolean check = StringHelper.isEmpty( protocol )
				|| "file".equals( protocol )
				|| "vfszip".equals( protocol )
				|| "vfsfile".equals( protocol );
		if ( !check ) {
			return url;
		}

		final String filePart = extractLocalFilePath( url );
		if ( filePart.startsWith( "/" ) ) {
			// the URL is already an absolute form
			return url;
		}
		else {
			// prefer to resolve the relative URL relative to the root PU URL per
			// JPA 2.0 clarification.
			final File rootUrlFile = new File( extractLocalFilePath( rootUrl ) );
			try {
				if ( rootUrlFile.isDirectory() ) {
					// The PU root is a directory (exploded).  Here we can just build
					// the relative File reference and use the Filesystem API to convert
					// to URI and then a URL
					final File combined = new File( rootUrlFile, filePart );
					// make sure it exists..
					if ( combined.exists() ) {
						return combined.toURI().toURL();
					}
				}
				else {
					// The PU root is an archive.  Here we have to build a JAR URL to properly
					// handle the nested entry reference (the !/ part).
					return new URL(
							"jar:" + protocol + "://" + rootUrlFile.getAbsolutePath() + "!/" + filePart
					);
				}
			}
			catch (MalformedURLException e) {
				// allow to pass through to return the original URL
				log.debugf(
						e,
						"Unable to adjust relative <jar-file/> URL [%s] relative to root URL [%s]",
						filePart,
						rootUrlFile.getAbsolutePath()
				);
			}

			return url;
		}
	}