code: private String replacementFor(String cn) {
          String name = cn;
          String value = null;
          while (value == null && name != null) {
              try {
                  value = ResourceBundleHelper.jdkinternals.getString(name);
              } catch (MissingResourceException e) {
                  // go up one subpackage level
                  int i = name.lastIndexOf('.');
                  name = i > 0 ? name.substring(0, i) : null;
              }
          }
          return value;
      }
docs: Returns the recommended replacement API for the given classname;
  or return null if replacement API is not known.