code: protected void fireChange(boolean force) {
  
          String value = getFormValueAsString();
          if (force || !value.equals(m_previousValue)) {
              m_previousValue = value;
              ValueChangeEvent.fire(this, value);
          }
      }
docs: Fires the value change event if the value has changed.<p>
  
  @param force <code>true</code> to force firing the event in any case