protected void notifyPropertyListeners(String propertyName, Object newValue, Object oldValue) {
   IssuePropertyChangeEvent event =
       new IssuePropertyChangeEvent(this, propertyName, newValue, oldValue);
   for (IIssueListener l : listeners) {
     l.notifyPropertyChanged(event);
   }
 }
 protected void notifyListeners(IssueChangeType type, Object newValue, Object oldValue) {
   IssueEvent event = new IssueEvent(this, type, newValue, oldValue);
   for (IIssueListener l : listeners) {
     l.notifyChanged(event);
   }
 }