docs: public static URL extractJarFileURL(URL jarUrl) throws MalformedURLException {
          String urlFile = jarUrl.getFile();
          int separatorIndex = urlFile.indexOf(JAR_URL_SEPARATOR);
          if (separatorIndex != -1) {
              String jarFile = urlFile.substring(0, separatorIndex);
              try {
                  return new URL(jarFile);
              } catch (MalformedURLException ex) {
                  // Probably no protocol in original jar URL, like "jar:C:/mypath/myjar.jar".
                  // This usually indicates that the jar file resides in the file system.
                  if (!jarFile.startsWith("/")) {
                      jarFile = "/" + jarFile;
                  }
                  return new URL(FILE_URL_PREFIX + jarFile);
              }
          }
          return jarUrl;
      }