[client] Fix HttpClient support for reading empty stream

http-client/src/main/java/io/avaje/http/client/DHttpClientRequest.java

@@ -585,7 +585,7 @@ private <T> Stream<T> stream(BodyReader<T> bodyReader) {
     final HttpResponse<Stream<String>> res = handler(HttpResponse.BodyHandlers.ofLines());
     this.httpResponse = res;
     checkResponse(res);
-    return res.body().map(bodyReader::readBody);
+    return res.body().filter(line -> !line.isEmpty()).map(bodyReader::readBody);
   }
 
   @Override

http-client/src/test/java/io/avaje/http/client/HelloControllerTest.java

@@ -271,6 +271,18 @@ void get_stream_as() {
     assertThat(first.name).isEqualTo("one");
   }
 
+  @Test
+  void get_stream_as_when_empty() {
+    final HttpResponse<Stream<SimpleData>> res = clientContext.request()
+      .path("hello").path("streamEmpty")
+      .GET()
+      .asStream(SimpleData.class);
+
+    assertThat(res.statusCode()).isEqualTo(200);
+    final List<SimpleData> data = res.body().collect(Collectors.toList());
+    assertThat(data).isEmpty();
+  }
+
   @Test
   void get_stream_NotFoundException() {
     clientContext.metrics(true);

http-client/src/test/java/org/example/webserver/HelloController$Route.java

@@ -52,6 +52,11 @@ private void routes(JavalinDefaultRouting cfg) {
       controller.stream(ctx);
     });
 
+    cfg.get("/hello/streamEmpty", ctx -> {
+      ctx.status(200);
+      controller.streamEmpty(ctx);
+    });
+
     cfg.get("/hello/{id}/{date}", ctx -> {
       ctx.status(200);
       final int id = asInt(ctx.pathParam("id"));

http-client/src/test/java/org/example/webserver/HelloController.java

@@ -63,6 +63,13 @@ void stream(Context context) {
     context.result(content);
   }
 
+  @Get("streamEmpty")
+  void streamEmpty(Context context) {
+    // simulate x-json-stream response with empty stream
+    context.header("content-type", "application/x-json-stream");
+    context.result("\n");
+  }
+
   /**
    * Return the Hello DTO.
    *