Fixes where vert.x span ended prior to response headers

Before, we accidentally ended a span when the request ended, vs when
response headers were sent. This prevents that and also removes
unnecessary duplication of handler code which was blindly copied from
opentracing as opposed to tested to see if actually necessary.

instrumentation/vertx-web/pom.xml

@@ -12,7 +12,7 @@
 
   <properties>
     <main.basedir>${project.basedir}/../..</main.basedir>
-    <vertx.version>3.4.2</vertx.version>
+    <vertx.version>3.5.1</vertx.version>
     <main.java.version>1.8</main.java.version>
     <main.signature.artifact>java18</main.signature.artifact>
   </properties>

instrumentation/vertx-web/src/main/java/brave/vertx/web/TracingRoutingContextHandler.java

@@ -12,6 +12,7 @@
 import io.vertx.core.http.HttpServerResponse;
 import io.vertx.core.net.SocketAddress;
 import io.vertx.ext.web.RoutingContext;
+import java.util.concurrent.atomic.AtomicBoolean;
 import zipkin2.Endpoint;
 
 /**
@@ -71,10 +72,6 @@ final class TracingRoutingContextHandler implements Handler<RoutingContext> {
     Span span = serverHandler.handleReceive(extractor, context.request());
     TracingHandler handler = new TracingHandler(context, span);
     context.put(TracingHandler.class.getName(), handler);
-
-    // When a route ends a request directly, this will finish the span
-    context.request().endHandler(handler);
-    // When a route overwrites the above endHandler, this will finish the span
     context.addHeadersEndHandler(handler);
 
     try (Tracer.SpanInScope ws = tracer.withSpanInScope(span)) {
@@ -85,14 +82,15 @@ final class TracingRoutingContextHandler implements Handler<RoutingContext> {
   class TracingHandler implements Handler<Void> {
     final RoutingContext context;
     final Span span;
+    final AtomicBoolean finished = new AtomicBoolean();
 
     TracingHandler(RoutingContext context, Span span) {
       this.context = context;
       this.span = span;
     }
 
     @Override public void handle(Void aVoid) {
-      if (!context.request().isEnded()) return;
+      if (!finished.compareAndSet(false, true)) return;
       Route route = new Route(context.request().rawMethod(), context.currentRoute().getPath());
       try {
         currentRoute.set(route);

instrumentation/vertx-web/src/main/java/brave/vertx/web/VertxWebTracing.java

@@ -15,10 +15,11 @@ public static VertxWebTracing create(HttpTracing httpTracing) {
     return new VertxWebTracing(httpTracing);
   }
 
-  final Handler<RoutingContext> routingContextHandler;
+  final HttpTracing httpTracing;
 
   VertxWebTracing(HttpTracing httpTracing) {
-    routingContextHandler = new TracingRoutingContextHandler(httpTracing);
+    if (httpTracing == null) throw new NullPointerException("httpTracing == null");
+    this.httpTracing = httpTracing;
   }
 
   /**
@@ -34,6 +35,6 @@ public static VertxWebTracing create(HttpTracing httpTracing) {
    * }</pre>
    */
   public Handler<RoutingContext> routingContextHandler() {
-    return routingContextHandler;
+    return new TracingRoutingContextHandler(httpTracing);
   }
 }