Configure the StatisticsHandler correctly (#2)

* Fixes #1
* Used the following code snippet from Jetty as a reference: https://github.com/eclipse/jetty.project/blob/aa52d67dbf8b46f393988cbd3ee65a8172c8e380/jetty-runner/src/main/java/org/eclipse/jetty/runner/Runner.java#L362

Author: dgroomes

programmatic/src/main/java/dgroomes/wiremock/App.java

@@ -13,7 +13,7 @@
 public class App {
 
     private static final Logger log = LoggerFactory.getLogger(App.class);
-    public static final int SLEEP_SECONDS = 1;
+    public static final int SLEEP_SECONDS = 5;
 
     public static void main(String[] args) throws InterruptedException {
         WireMockConfiguration options = WireMockUtil.shutdownGracefully(new WireMockConfiguration());

programmatic/src/main/java/dgroomes/wiremock/WireMockUtil.java

@@ -7,7 +7,7 @@
 import com.github.tomakehurst.wiremock.http.StubRequestHandler;
 import com.github.tomakehurst.wiremock.jetty9.JettyHttpServerFactory;
 import com.github.tomakehurst.wiremock.jetty94.Jetty94HttpServer;
-import org.eclipse.jetty.server.Handler;
+import org.eclipse.jetty.server.handler.HandlerCollection;
 import org.eclipse.jetty.server.handler.StatisticsHandler;
 
 /**
@@ -37,8 +37,15 @@ public HttpServer buildHttpServer(Options options, AdminRequestHandler adminRequ
                 return new Jetty94HttpServer(options, adminRequestHandler, stubRequestHandler) {
 
                     @Override
-                    protected Handler[] extensionHandlers() {
-                        return new Handler[]{new StatisticsHandler()};
+                    protected HandlerCollection createHandler(Options options, AdminRequestHandler adminRequestHandler, StubRequestHandler stubRequestHandler) {
+                        var handlers = super.createHandler(options, adminRequestHandler, stubRequestHandler);
+                        var statisticsHandler = new StatisticsHandler();
+                        statisticsHandler.setHandler(handlers);
+                        // Unfortunately, the statisticsHandler needs to be wrapped in a HandlerCollection because the
+                        // super method must return the type "HandlerCollection", but really the method can afford to
+                        // return the more generic type "Handler". So we must accommodate the unnecessarily specific
+                        // type signature.
+                        return new HandlerCollection(statisticsHandler);
                     }
                 };
             }