code: public void visit(final WebAppServlet webAppServlet) {
  		NullArgumentException.validateNotNull(webAppServlet, "Web app servlet");
  		final String[] urlPatterns = webAppServlet.getAliases();
  		if (urlPatterns == null || urlPatterns.length == 0) {
  			LOG.warn("Servlet [" + webAppServlet
  					+ "] does not have any mapping. Skipped.");
  		}
  		try {
  			if (webAppServlet instanceof WebAppJspServlet) {
  				webContainer.registerJspServlet(urlPatterns, httpContext,
  						((WebAppJspServlet) webAppServlet).getJspPath());
  			} else {
  				Class<? extends Servlet> servletClass = RegisterWebAppVisitorHS
  						.loadClass(Servlet.class, bundleClassLoader,
  								webAppServlet.getServletClassName());
  				webContainer.registerServlet(servletClass, urlPatterns,
  						RegisterWebAppVisitorHS.convertInitParams(webAppServlet
  								.getInitParams()), webAppServlet
  								.getLoadOnStartup(), webAppServlet
  								.getAsyncSupported(), webAppServlet.getMultipartConfig()
  						, httpContext);
  			}
  			//CHECKSTYLE:OFF
  		} catch (Exception ignore) {
  			LOG.error(REGISTRATION_EXCEPTION_SKIPPING, ignore);
  		}
  		//CHECKSTYLE:ON
  	}
docs: Registers servlets with web container.
  
  @throws NullArgumentException if servlet is null
  @see WebAppVisitor#visit(org.ops4j.pax.web.extender.war.internal.model.WebAppServlet)