code: protected void checkTemplate() {
  
          if (CmsStringUtil.isEmptyOrWhitespaceOnly(m_simpleFieldFolderName.getValue())) {
              return;
          }
          if (!m_clonedCms.existsResource(getSiteRoot())) {
              return;
          }
          try {
              String templateValue = m_clonedCms.readPropertyObject(
                  getSiteRoot(),
                  CmsPropertyDefinition.PROPERTY_TEMPLATE,
                  false).getValue();
              m_simpleFieldTemplate.addItem(templateValue);
              m_simpleFieldTemplate.setValue(templateValue);
          } catch (CmsException e) {
              //
          }
      }
docs: Checks the Template Property of the site root and fills the form field.<p>