code: @SuppressWarnings({"UnusedDeclaration"})
      public void doIndex(StaplerRequest req, StaplerResponse resp) throws IOException, ServletException {
          req.getView(this, chooseAction()).forward(req, resp);
      }
docs: Select which view to display based on the state of the promotion. Will return the form if user selects to perform
  promotion. Progress will be returned if the promotion is currently in progress.