code: private void notifyOnValidationFailure(@NonNull final Validator<CharSequence> validator) {
          for (ValidationListener<CharSequence> validationListener : validationListeners) {
              validationListener.onValidationFailure(this, validator);
          }
      }
docs: Notifies the listeners that the validation of the dialog's edit text widget has failed.
  
  @param validator
  The validator, which caused the validation to fail, as an instance of the type {@link
  Validator}. The validator may not be null