Remove the following deprecated RPC definitions that were announced for
removal in 0.21 via the 0.20 release notes:
lnrpc:
- SendPayment (bidirectional streaming)
- SendPaymentSync
- SendToRoute (bidirectional streaming)
- SendToRouteSync
routerrpc:
- SendPayment (streaming)
- SendToRoute
- TrackPayment (streaming)
Also remove the now-unused PaymentState enum and PaymentStatus message
that were only used by the deprecated TrackPayment response stream, plus
the corresponding REST annotations from the yaml files.
Drop the now-orphan routerrpc.SendToRouteResponse message that was only
referenced by the deleted routerrpc.SendToRoute RPC.
Also remove the deprecated outgoing_chan_id field from
lnrpc.QueryRoutesRequest (tag 14) and routerrpc.SendPaymentRequest
(tag 8); their tag numbers are now reserved. Callers must use the
multi-channel outgoing_chan_ids field introduced in 0.20.
Drop the compat fallback in router_backend.go that previously consumed
the field, and regenerate all protobuf, gRPC, REST gateway, JSON, and
swagger files.
The grpc-gateway library that is used to transform REST calls into gRPC
uses a different method for reading a request body stream depending on
whether the RPC is a request-streaming one or not. We can't really find
out what kind of RPC the user is calling at runtime, so we add a new
parameter to the proxy that lists all request-streaming RPC calls.
In any case the client _has_ to send one request message initially to
kick off the request processing. Normally this can just be an empty
message. This can lead to problems if that empty message is not
expected by the gRPC server. But for the currently existing two
client-streaming RPCs this will only trigger a warning
(HTLC interceptor) or be ignored (channel acceptor).
