docs: public ServletRegistration.Dynamic addServlet(String name, Servlet servlet) {
          final ServletHolder holder = new NonblockingServletHolder(requireNonNull(servlet));
          holder.setName(name);
          handler.getServletHandler().addServlet(holder);
  
          final ServletRegistration.Dynamic registration = holder.getRegistration();
          checkDuplicateRegistration(name, servlets, "servlet");
  
          return registration;
      }