code: @Override
      public void describeMismatch(final Object item, final Description description) {
          final T value;
          try {
              value = this.retrieveValue((Request) item);
          } catch (Exception ex) {
              throw new JadlerException("An error occurred while retrieving a value from the http request "
                      + "for mismatch description", ex);
          }
  
          description.appendText("REQUIRED: ");
          description.appendDescriptionOf(this);
          description.appendText(" BUT ");
          this.pred.describeMismatch(value, description);
      }
docs: {@inheritDoc}