Function grpc_request 

pub fn grpc_request(headers: &HeaderMap, version: Version) -> bool

Whether a request is gRPC (DW-039): HTTP/2 with an application/grpc content type (the spec’s family prefix — application/grpc+proto, +json, … all match).

(Public for the DW-039 unit tests; like strip_hop_by_hop, not part of the stable public surface.)