Add java.net.http.HttpClientHttpSigV4Signer

[magutierrm]

Hello,
Ever since Apache Jena SPARQL version 4.2.0, the default HttpClient in use has been java.net.http.HttpClient. However, there is currently no implementation of a Signer available for this specific HTTP client. Are there any plans on your end to provide support for it?
Thank you in advance.

See https://jena.apache.org/documentation/sparql-apis/

[MuhdSayeed]

Any updates ? :)

[Cameronjmayfield]

Looking for this as well.

[spmallette]

i spent a bit of time on this today thinking it would be relatively easy to do, but it didn't turn out the way. the progress went like this:

• still building to jdk8 technically, so we'd have to make the decision to go to java11. trie a multi-release project to support 8 and 11+ and it might not be the right use case for this since the changes would require API level differences to work and that doesn't make sense really. also ran into problems with build tooling still not fully supporting the multi-release project style (particularly surefire).
• certain test common to the test suite didn't make sense for Java HTTP and how it works...took a while to figure out what to do with those since i wasn't wholly familiar with this library.
• unlike other http libraries, java HttpRequest is immutable, so the standard approach to modifying an existing request, which this whole library is based on, becomes problematic.
• while looking at that issue, i realized that there's no interceptor for the Java 'HttpClient' so you can't modify requests given to it. For this to work with Jena's RDFConnectionRemoteBuilder i guess we'd have to extend the HttpClient to do any sort of manipulation of the request.

anyway, i need to step away from this for a bit and the change probably needs soem feedback, but it's a step in the direction to getting the Jena dependency upgraded. here's the branch that i've simplified to just use java 11: https://github.com/aws/amazon-neptune-sigv4-signer/compare/stepmall-java-http