code: @UiHandler("m_submitButton")
      public void onClickSubmit(ClickEvent event) {
  
          String separator = ",";
          String selectedValue = m_separator.getText().trim();
          if (!CmsStringUtil.isEmptyOrWhitespaceOnly(selectedValue)) {
              separator = selectedValue;
          }
          m_separatorField.setValue(separator);
          m_formPanel.submit();
      }
docs: The event handler for the submit button.<p>
  
  @param event the click event