code: @UiHandler("m_okButton")
      void onClickOk(ClickEvent e) {
  
          String propName = m_propertyNameField.getFormValueAsString();
          if (CmsStringUtil.isEmptyOrWhitespaceOnly(propName)) {
              m_propertyNameField.setErrorMessage(CmsPropertyDefinitionMessages.messageEmpty());
              return;
          }
          String normalizedName = propName.trim();
          if (!isValidName(normalizedName)) {
              m_propertyNameField.setErrorMessage(CmsPropertyDefinitionMessages.messageInvalidName());
              return;
          }
          if (m_existingPropertyNames.contains(normalizedName)) {
              m_propertyNameField.setErrorMessage(CmsPropertyDefinitionMessages.alreadyExists());
              return;
          }
          savePropertyDefinitionAndQuit(normalizedName);
      }
docs: Button handler for the OK button.<p>
  
  @param e the click event