code: private void addError(int code, String key) {
  
          errorCodes = (int[]) ArrayUtil.resizeArray(errorCodes,
                  errorCodes.length + 1);
          errorKeys = (String[]) ArrayUtil.resizeArray(errorKeys,
                  errorKeys.length + 1);
          errorCodes[errorCodes.length - 1] = code;
          errorKeys[errorKeys.length - 1]   = key;
      }
docs: Adds the error code and the key to the list of errors. This list
  is populated during construction or addition of elements and is used
  outside this class to act upon the errors.