fn handle_negotiation_request(
core: &mut ProtocolCore,
request_id: RequestId,
kind: NegotiationKind,
payload: SessionDescriptionPayload,
) -> Vec<Command>fn handle_negotiation_request(
core: &mut ProtocolCore,
request_id: RequestId,
kind: NegotiationKind,
payload: SessionDescriptionPayload,
) -> Vec<Command>