code: public static String getStringFromBundle(Class<?> caller, String bundleName, String key, String defaultString) {
          if (resolver == null)
              resolver = TraceNLSResolver.getInstance();
  
          return resolver.getMessage(caller, null, bundleName, key, null, defaultString, false, null, false);
      }
docs: Retrieve the localized text corresponding to the specified key in the
  specified ResourceBundle. If the text cannot be found for any reason, the
  defaultString is returned. If an error is encountered, an appropriate
  error message is returned instead.
  <p>
  
  @param caller
  Class object calling this method
  @param bundleName
  the fully qualified name of the ResourceBundle. Must not be
  null.
  @param key
  the key to use in the ResourceBundle lookup. Must not be null.
  @param defaultString
  text to return if text cannot be found. Must not be null.
  @return the value corresponding to the specified key in the specified
  ResourceBundle, or the appropriate non-null error message.