trailer metadata.MD,
throttledLogger log.ThrottledLogger,
) (trailerMetadata map[string]string, propagatedMetadata map[string]string) {
trailer_to_context_metadata_interceptor.go
trailerMetadata = make(map[string]string)
propagatedMetadata = make(map[string]string)
// Try proto format first (authoritative).
if values := trailer[protoTrailerKey]; len(values) > 0 {
protoMsg := &contextpropagationspb.ContextMetadata{}
err := proto.Unmarshal([]byte(values[0]), protoMsg)