code: public void setDataDismiss(final ButtonDismiss dismiss) {
          if (dismiss != null) {
              getElement().setAttribute(Attributes.DATA_DISMISS, dismiss.getDismiss());
          } else {
              getElement().removeAttribute(Attributes.DATA_DISMISS);
          }
      }
docs: Sets dismiss type of button.
  <p/>
  If button is inside a
  {@link org.gwtbootstrap3.client.ui.Modal} and dismiss type is
  {@code MODAL} the button will act as the dismiss (close) button for this
  Modal. Same goes for {@link org.gwtbootstrap3.client.ui.Alert}
  and dismiss type {@code ALERT}.
  
  @param dismiss Dismiss type of button
  @see org.gwtbootstrap3.client.ui.Modal
  @see org.gwtbootstrap3.client.ui.Alert