code: private void defaultMessageResourcesConfig(ModuleConfig config) {
  
          String value = null;
  
          MessageResourcesConfig mrc =
              config.findMessageResourcesConfig(Globals.MESSAGES_KEY);
          if (mrc == null) {
              mrc = new MessageResourcesConfig();
              mrc.setKey(Globals.MESSAGES_KEY);
              config.addMessageResourcesConfig(mrc);
          }
          value = getServletConfig().getInitParameter("application");
          if (value != null) {
              mrc.setParameter(value);
          }
          value= getServletConfig().getInitParameter("factory");
          if (value != null) {
              mrc.setFactory(value);
          }
          value = getServletConfig().getInitParameter("null");
          if (value != null) {
              if (value.equalsIgnoreCase("true") ||
                  value.equalsIgnoreCase("yes")) {
                  mrc.setNull(true);
              } else {
                  mrc.setNull(false);
              }
          }
      }
docs: Perform backwards-compatible configuration of the default module's
  message resources configuration from servlet initialization parameters
  (as were used in Struts 1.0).
  
  @param config The ModuleConfig object for the default module
  
  @since Struts 1.1
  @deprecated Will be removed in a release after Struts 1.1.