code: public KeyChangeResult handleKeyChange(EntryChangeEvent event, boolean allLanguages) {
  
          if (m_keyset.getKeySet().contains(event.getNewValue())) {
              m_container.getItem(event.getItemId()).getItemProperty(TableProperty.KEY).setValue(event.getOldValue());
              return KeyChangeResult.FAILED_DUPLICATED_KEY;
          }
          if (allLanguages && !renameKeyForAllLanguages(event.getOldValue(), event.getNewValue())) {
              m_container.getItem(event.getItemId()).getItemProperty(TableProperty.KEY).setValue(event.getOldValue());
              return KeyChangeResult.FAILED_FOR_OTHER_LANGUAGE;
          }
          return KeyChangeResult.SUCCESS;
      }
docs: Handles a key change.
  
  @param event the key change event.
  @param allLanguages <code>true</code> for changing the key for all languages, <code>false</code> if the key should be changed only for the current language.
  @return result, indicating if the key change was successful.