com.google.api.gax.httpjson.ManagedHttpJsonInterceptorChannel does not close the channels correctly

[nitikhadapkar]

Environment details

1. Specify the artifact at the beginning of the title. For example, "api-common", "gax" etc)
2. OS type and version: Linux Debian 6.1.158-1 (2025-11-09) x86_64 GNU/Linux
3. Java version: openjdk version "11.0.20.1" 2023-08-24
4. artifact version(s): 2.63.1

Steps to reproduce

1. Created a GCP API stub which uses "defaultHttpJsonTransportProviderBuilder" and creates an "InstantiatingHttpJsonChannelProvider"
2. On the client close, the close is successfully but the executor service is not being deleted.

Code example

ManagedHttpJsonInterceptorChannel(
      ManagedHttpJsonChannel channel, HttpJsonClientInterceptor interceptor) {
    super();
    this.channel = channel;
    this.interceptor = interceptor;
  }

@Override
  public synchronized void shutdown() {
    channel.shutdown();
  }

super() calls ManagedHttpJsonChannel which creates a fixed executor service that never gets deleted.

protected ManagedHttpJsonChannel() {
    this(null, true, null, null);
  }

private ManagedHttpJsonChannel(
      Executor executor,
      boolean usingDefaultExecutor,
      String endpoint,
      @Nullable HttpTransport httpTransport) {
    this.executor = executor;
    this.usingDefaultExecutor = usingDefaultExecutor;
    this.endpoint = endpoint;
    this.httpTransport = httpTransport == null ? new NetHttpTransport() : httpTransport;
    this.deadlineScheduledExecutorService = Executors.newSingleThreadScheduledExecutor();
  }

Ideally we should call:

@Override
  public synchronized void shutdown() {
    super.shutdown();
    channel.shutdown();
  }

Same applies to shutdownNow(), close()