code: private void addExecutionListener(final ActivityImpl activity) {
      final String guardClass = guardClass(activity);
  
      if (isNotBlank(guardClass)) {
        activity.addExecutionListener(ExecutionListener.EVENTNAME_START, classDelegateFor(guardClass));
        activity.addExecutionListener(ExecutionListener.EVENTNAME_END, classDelegateFor(guardClass));
      }
    }
docs: Adds aa {@link ActivityGuard} on {@link ExecutionListener#EVENTNAME_START}
  and {@link ExecutionListener#EVENTNAME_END} if one is configured in the
  properties file.
  
  @param activity
  the current Activity in process