private class ValidatorTaskDataModelListener extends TaskDataModelListener {
@Override
public void attributeChanged(TaskDataModelEvent event) {
ErrorMessageCollector collector = validator.validateTaskAttribute(getModel().getTaskData(), event.getTaskAttribute());
if(collector!=null && collector.hasErrors()) {
getTaskEditor().setMessage(collector.getFirstErrorMessage(), IMessageProvider.WARNING);
} else {
getTaskEditor().setMessage("", IMessageProvider.NONE); //$NON-NLS-1$
}
}