code: public final SC registerServlet(Class<? extends HttpServlet> servletClass) {
  
          WebServlet webServlet = servletClass.getAnnotation(WebServlet.class);
  
          if (webServlet == null)
              throw new IllegalArgumentException(String.format("Missing annotation '%s' for class '%s'", WebFilter.class.getName(), servletClass.getName()));
  
          String[] urlPatterns = webServlet.value();
  
          if (urlPatterns.length == 0)
              urlPatterns = webServlet.urlPatterns();
  
          if (urlPatterns.length == 0)
              throw new IllegalArgumentException(String.format("Missing pattern mapping for '%s'", servletClass.getName()));
  
          for (String urlPattern : urlPatterns) {
              registerServlet(servletClass, urlPattern);
          }
  
          return (SC) this;
      }
docs: Registers a servlet.
  
  @param servletClass servlet class to be registered. This class must be annotated with {@linkplain WebServlet}.
  @return this.