code: public String getFormattedMessage(String key, Object[] args, String defaultString, boolean quiet) {
          if (resolver == null)
              resolver = TraceNLSResolver.getInstance();
  
          return resolver.getMessage(caller, null, ivBundleName, key, args, defaultString, true, null, quiet);
      }
docs: Return the message obtained by looking up the localized text indicated by
  the key in the ResourceBundle wrapped by this instance, then formatting
  the message using the specified arguments as substitution parameters.
  <p>
  The message is formatted using the java.text.MessageFormat class.
  Substitution parameters are handled according to the rules of that class.
  Most noteably, that class does special formatting for native java Date and
  Number objects.
  <p>
  If an error occurs in obtaining the localized text corresponding to this
  key, then the defaultString is used as the message text. If all else fails,
  this class will provide one of the default English messages to indicate
  what occurred.
  <p>
  
  @param key
  the key to use in the ResourceBundle lookup. Null is tolerated
  @param args
  substitution parameters that are inserted into the message
  text. Null is tolerated
  @param defaultString
  text to use if the localized text cannot be found. Null is
  tolerated
  @param quiet
  indicates whether or not errors will be logged when
  encountered
  <p>
  @return a non-null message that is localized and formatted as
  appropriate.