pub fn http_headers_to_grpc_metadata(
headers: &HeaderMap,
forwarded_headers: &[String],
) -> MetadataMapExpand description
Extract HTTP headers into a gRPC MetadataMap.
Forwards the headers listed in forwarded_headers, then always propagates
W3C trace-context (forwarding an incoming traceparent or synthesizing one
so the upstream joins a single trace across the REST↔gRPC boundary).