docs: protected void validateSingle(
          CmsUUID structureId,
          Map<String, String> sitePaths,
          String newSitePath,
          final AsyncCallback<String> errorCallback) {
  
          Map<String, String> newMap = new HashMap<String, String>(sitePaths);
          newMap.put("NEW", newSitePath); //$NON-NLS-1$
          AsyncCallback<Map<String, String>> callback = new AsyncCallback<Map<String, String>>() {
  
              public void onFailure(Throwable caught) {
  
                  assert false; // should never happen
              }
  
              public void onSuccess(Map<String, String> result) {
  
                  String newRes = result.get("NEW"); //$NON-NLS-1$
                  errorCallback.onSuccess(newRes);
              }
          };
          validateAliases(structureId, newMap, callback);
      }