code: private void selectDistributionSetValue() {
          selectedDefaultDisSetType = (Long) combobox.getValue();
          if (!selectedDefaultDisSetType.equals(currentDefaultDisSetType)) {
              changeIcon.setVisible(true);
              notifyConfigurationChanged();
          } else {
              changeIcon.setVisible(false);
          }
      }
docs: Method that is called when combobox event is performed.