The "use-gvariant" property denotes if [structGLib.Variant] should be used to
communicate with the peer instead of JSON. You should only set this
if you know the peer is also a Jsonrpc-GLib based client.
Setting this property allows the peers to communicate using GVariant
instead of JSON. This means that we can access the messages without
expensive memory allocations and parsing costs associated with JSON.
[structGLib.Variant] is much more optimal for memory-bassed message passing.
The "io-stream" property is the [class
Gio.IOStream] to use for communicating with a JSON-RPC peer.