code: public void configure(StaplerRequest req, JSONObject formData) throws IOException, ServletException, FormException {
          configure(formData);
      }
docs: Handles the submission for the system configuration.
  
  <p>
  If this class defines {@code config.jelly} view, be sure to
  override this method and persists the submitted values accordingly.
  
  <p>
  The following is a sample {@code config.jelly} that you can start yours with:
  <pre>{@code <xmp>
  <j:jelly xmlns:j="jelly:core" xmlns:st="jelly:stapler" xmlns:d="jelly:define" xmlns:l="/lib/layout" xmlns:t="/lib/hudson" xmlns:f="/lib/form">
  <f:section title="Locale">
  <f:entry title="${%Default Language}" help="/plugin/locale/help/default-language.html">
  <f:textbox name="systemLocale" value="${it.systemLocale}" />
  </f:entry>
  </f:section>
  </j:jelly>
  </xmp>}</pre>
  
  <p>
  This allows you to access data as {@code formData.getString("systemLocale")}
  
  <p>
  If you are using this method, you'll likely be interested in
  using {@link #save()} and {@link #load()}.
  @since 1.305