code: @Override
      public HandlerRegistration addValueChangeHandler(final ValueChangeHandler<Date> dateValueChangeHandler) {
          textBox.addValueChangeHandler(new ValueChangeHandler<String>() {
              @Override
              public void onValueChange(ValueChangeEvent<String> event) {
                  ValueChangeEvent.fire(DatePickerBase.this, getValue());
              }
          });
          return addHandler(dateValueChangeHandler, ValueChangeEvent.getType());
      }
docs: {@inheritDoc}