Add httpProtocol method to WebServiceClient.Builder

[ggabora]

• Added httpVersion() method on WebServiceClient.Builder
  which allows configuring HTTP protocol version (HTTP/1.1 or HTTP/2) for web
  service requests.
• Updated README.md with comprehensive HTTP protocol configuration documentation.
• Added detailed information about HTTP version settings, proxy configuration,
  timeout settings, authentication, and connection management.
• Improved documentation for developers using the web service client.

[horgh]

Hi! Thanks for the PR.

Could you tell me about the use case for this option? I think generally HTTP/1.1 should be discouraged, e.g. https://http1mustdie.com/, so I'm not sure about adding something new to enable it.

[ggabora]

@horgh Hi, we have a case when we get connection reset on the WebServiceClient connections because of network/firewall inbetween our app and maxmind. In other cases where we use HttpClient with http/1.1 we set the jdk keepalive timeout to a lower value than the one of the network/firewall so that the connections in the pool are 'evicted' sooner. In case of http/2 there is no such option so the simplest solution for us would be to downgrade to http/1.1.
A better approach would be to somehow be able to have access to the http/2 connections of the WebServiceClient and 'evict' them when needed or implement a resilience mechanism inside WebServiceClient to handle connection reset cases and recreate the connection.
Another solution would be to create a WebServiceClient per request but event that is a bit hard since there is no close() logic like it was in previous versions.

Thanks!

[ggabora]

Btw, maybe an increase in the minor version is more appropriate for this change?

[horgh]

Thanks for the background!

It looks like there is a similar setting to the one you mentioned for HTTP/1.1 that applies for HTTP/2 connections: jdk.httpclient.keepalive.timeout.h2. The docs say that it falls back to using jdk.httpclient.keepalive.timeout if it's not set. Would using this setting work for you?

[ggabora]

It would work if we could use Java 20 where this change was introduced https://bugs.openjdk.org/browse/JDK-8295649
Currently we are using java 17. I'll check what it would take to migrate to java 20 or higher and get back.
Thanks!

[ggabora]

Morning, migrating to java 20+ is not possible in the near future, so we're stuck with this fix.

[horgh]

I see. To that end, I've added a method to the builder called httpClient() which would let you pass in an HttpClient configured as you need it. I think that'd be more of an API we'd want to support, rather than having something specific to HTTP/1.1 See #592.

[ggabora]

Great, thank you! When is the next release scheduled?

[ggabora]

Not needed anymore because it is solved by #592

[horgh]

I think we should be able to release in the next day or two!

[horgh]

We released 4.4.0 with this! https://central.sonatype.com/artifact/com.maxmind.geoip2/geoip2

[ggabora]

Great, thank you again for your help!