Prepare for switching to JSON-LD 1.1 as the default.

Prepare for switching to JSON-LD 1.1 as the default.

This is complicated by the fact that, with Java11, java.net.http fails to setup the HTTP/2 connection to schema.org.

Works with Java17.

The java.net.http handling is within Titanium; it is not the switchable RIOT default HttpClient.

It is not a titanium bug - it is reproducible without Titanium.