Feign OKHttpClient with Http2 - okhttp

Question

I set up a basic http2 client with okhttp
http2 is enabled for the URL below.
#FeignClient(name = "client", url = "https://http2.pro/api/v1", configuration = FeignConfig.class)
public interface TestClient {
#GetMapping("/")
String callServer();
}
feign.client.config.default.logger-level=full
feign.okhttp.enabled=true
logging.level.com.example=DEBUG
logging.level.okhttp3=DEBUG
When I hit this service in the logs I see HTTP 1.1.
Since I already know this service is using Http2
How can i enforce my client to use HTTP 2 protocol.
om.example.http2clientpoc.TestClient : [TestClient#callServer] ---> GET https://http2.pro/api/v1/ HTTP/1.1
2023-02-07 12:42:53.704 DEBUG 53855 --- [ main] com.example.http2clientpoc.TestClient : [TestClient#callServer] ---> END HTTP (0-byte body)
2023-02-07 12:42:54.080 DEBUG 53855 --- [ main] okhttp3.internal.http2.Http2 : >> CONNECTION 505249202a20485454502f322e300d0a0d0a534d0d0a0d0a
2023-02-07 12:42:54.081 DEBUG 53855 --- [ main] okhttp3.internal.http2.Http2 : >> 0x00000000 6 SETTINGS
2023-02-07 12:42:54.081 DEBUG 53855 --- [ main] okhttp3.internal.http2.Http2 : >> 0x00000000 4 WINDOW_UPDATE
Prior knowledge is not working (exception message : H2_PRIOR_KNOWLEDGE cannot be used with HTTPS)
#Bean
OkHttpClient httpClient() {
return new OkHttpClient(new okhttp3.OkHttpClient.Builder()
.protocols(List.of(Protocol.H2_PRIOR_KNOWLEDGE)).build());
}

Answer 1

Try this:
#Bean
OkHttpClient httpClient() {
return new OkHttpClient(new okhttp3.OkHttpClient.Builder()
.protocols(List.of(Protocol.H2)).build());
}