fix: Fail ITHeadersTest if server does not respond to request, rather than later NPE.

Author: burkedavison

java-compute/google-cloud-compute/src/test/java/com/google/cloud/compute/v1/integration/ITHeadersTest.java

@@ -73,19 +73,14 @@ public static void tearDown() {
   }
 
   @Test
-  public void testHeaders() {
+  public void testHeaders() throws TimeoutException, ExecutionException, InterruptedException {
     OperationFuture<Operation, Operation> future =
         addressesClient.insertAsync(
             "testProject", "testRegion", Address.newBuilder().setName("testName").build());
-    try {
-      future.get(5, TimeUnit.SECONDS);
-    } catch (InterruptedException | ExecutionException e) {
-      e.printStackTrace();
-    } catch (TimeoutException e) {
-      ; // expected
-    }
-    future.cancel(true);
 
+    future.get(30, TimeUnit.SECONDS);
+
+    Assert.assertNotNull("Server did not process request headers.", headers);
     List<String> clientIdentificationHeader = headers.get("X-goog-api-client");
     Assert.assertNotNull(
         "X-goog-api-client header missing. Headers found: " + String.join(", ", headers.keySet()),