code: @SuppressWarnings("unchecked")
      private void loadServlets(Map<String, ServletConfiguration> servlets, Environment environment) throws ClassNotFoundException {
          if (servlets != null) {
              for (Map.Entry<String, ServletConfiguration> servletEntry : servlets.entrySet()) {
                  ServletConfiguration servlet = servletEntry.getValue();
  
                  // Create servlet holder
                  ServletHolder servletHolder = new ServletHolder((Class<? extends Servlet>) Class.forName(servlet.getClazz()));
  
                  // Set name of servlet
                  servletHolder.setName(servletEntry.getKey());
  
                  // Set params
                  if (servlet.getParam() != null) {
                      for (Map.Entry<String, String> entry : servlet.getParam().entrySet()) {
                          servletHolder.setInitParameter(entry.getKey(), entry.getValue());
                      }
                  }
  
                  // Add servlet
                  environment.getApplicationContext().addServlet(servletHolder, servlet.getUrl());
              }
          }
      }
docs: Load all servlets.