code: public static void addActionError( ServletRequest request, String propertyName, String messageKey,
                                         Object messageArg1, Object messageArg2 )
      {
          Object[] messageArgs = new Object[]{ messageArg1, messageArg2 };
          InternalUtils.addActionError( propertyName, new ActionMessage( messageKey, messageArgs ), request );
      }
docs: Add a property-related message that will be shown with the Errors and Error tags.
  
  @param request the current ServletRequest.
  @param propertyName the name of the property with which to associate this error.
  @param messageKey the message-resources key for the message.
  @param messageArg1 the first argument to the message
  @param messageArg2 the second argument to the message