chore: normalize host URL in MultipartUploadHttpRequestManager

google-cloud-storage/src/main/java/com/google/cloud/storage/MultipartUploadHttpRequestManager.java

@@ -253,7 +253,11 @@ static MultipartUploadHttpRequestManager createFrom(HttpStorageOptions options)
         storage.getRequestFactory(),
         new XmlObjectParser(new XmlMapper()),
         options.getMergedHeaderProvider(FixedHeaderProvider.create(stableHeaders.build())),
-        URI.create(options.getHost()));
+        URI.create(ensureTrailingSlash(options.getHost())));
+  }
+
+  private static String ensureTrailingSlash(String host) {
+    return host.endsWith("/") ? host : host + "/";
   }
 
   private void addChecksumHeader(@Nullable Crc32cLengthKnown crc32c, HttpHeaders headers) {

google-cloud-storage/src/test/java/com/google/cloud/storage/FakeHttpServer.java

@@ -93,6 +93,10 @@ public void close() throws Exception {
   }
 
   static FakeHttpServer of(HttpRequestHandler server) {
+    return of(server, true);
+  }
+
+  static FakeHttpServer of(HttpRequestHandler server, boolean trailingSlash) {
     // based on
     // https://github.com/netty/netty/blob/59aa6e635b9996cf21cd946e64353270679adc73/example/src/main/java/io/netty/example/http/helloworld/HttpHelloWorldServer.java
     InetSocketAddress address = new InetSocketAddress("localhost", 0);
@@ -124,7 +128,8 @@ protected void initChannel(SocketChannel ch) {
     Channel channel = b.bind(address).syncUninterruptibly().channel();
 
     InetSocketAddress socketAddress = (InetSocketAddress) channel.localAddress();
-    URI endpoint = URI.create("http://localhost:" + socketAddress.getPort() + "/");
+    String suffix = trailingSlash ? "/" : "";
+    URI endpoint = URI.create("http://localhost:" + socketAddress.getPort() + suffix);
     HttpStorageOptions httpStorageOptions =
         HttpStorageOptions.http()
             .setHost(endpoint.toString())

google-cloud-storage/src/test/java/com/google/cloud/storage/ITMultipartUploadHttpRequestManagerTest.java

@@ -1364,6 +1364,40 @@ public void sendListMultipartUploadsRequest_withUserProject() throws Exception {
     }
   }
 
+  @Test
+  public void hostWithoutTrailingSlash_urlConstructedCorrectly() throws Exception {
+    HttpRequestHandler handler =
+        req -> {
+          assertThat(req.uri()).startsWith("/test-bucket/test-key");
+          CreateMultipartUploadResponse response =
+              CreateMultipartUploadResponse.builder()
+                  .bucket("test-bucket")
+                  .key("test-key")
+                  .uploadId("test-upload-id")
+                  .build();
+          ByteBuf buf = Unpooled.wrappedBuffer(xmlMapper.writeValueAsBytes(response));
+          DefaultFullHttpResponse resp =
+              new DefaultFullHttpResponse(req.protocolVersion(), OK, buf);
+          resp.headers().set(CONTENT_TYPE, "application/xml; charset=utf-8");
+          return resp;
+        };
+
+    try (FakeHttpServer fakeHttpServer = FakeHttpServer.of(handler, false)) {
+      MultipartUploadHttpRequestManager manager =
+          MultipartUploadHttpRequestManager.createFrom(fakeHttpServer.getHttpStorageOptions());
+      CreateMultipartUploadRequest request =
+          CreateMultipartUploadRequest.builder()
+              .bucket("test-bucket")
+              .key("test-key")
+              .contentType("application/octet-stream")
+              .build();
+
+      CreateMultipartUploadResponse response = manager.sendCreateMultipartUploadRequest(request);
+
+      assertThat(response.bucket()).isEqualTo("test-bucket");
+    }
+  }
+
   private void forceSetUploads(
       ListMultipartUploadsResponse response, java.util.List<MultipartUpload> uploads) {
     try {