docs: private static JarFile _getAlternativeJarFile(URL url) throws IOException
      {
          String urlFile = url.getFile();
  
          // Trim off any suffix - which is prefixed by "!/" on Weblogic
          int separatorIndex = urlFile.indexOf("!/");
  
          // OK, didn't find that. Try the less safe "!", used on OC4J
          if (separatorIndex == -1)
          {
              separatorIndex = urlFile.indexOf('!');
          }
  
          if (separatorIndex != -1)
          {
              String jarFileUrl = urlFile.substring(0, separatorIndex);
              // And trim off any "file:" prefix.
              if (jarFileUrl.startsWith("file:"))
              {
                  jarFileUrl = jarFileUrl.substring("file:".length());
              }
  
              return new JarFile(jarFileUrl);
          }
  
          return null;
      }