TUN-5989: Add in-memory otlp exporter

vendor/github.com/grpc-ecosystem/grpc-gateway/v2/runtime/marshal_httpbodyproto.go

@@ -0,0 +1,32 @@
+package runtime
+
+import (
+	"google.golang.org/genproto/googleapis/api/httpbody"
+)
+
+// HTTPBodyMarshaler is a Marshaler which supports marshaling of a
+// google.api.HttpBody message as the full response body if it is
+// the actual message used as the response. If not, then this will
+// simply fallback to the Marshaler specified as its default Marshaler.
+type HTTPBodyMarshaler struct {
+	Marshaler
+}
+
+// ContentType returns its specified content type in case v is a
+// google.api.HttpBody message, otherwise it will fall back to the default Marshalers
+// content type.
+func (h *HTTPBodyMarshaler) ContentType(v interface{}) string {
+	if httpBody, ok := v.(*httpbody.HttpBody); ok {
+		return httpBody.GetContentType()
+	}
+	return h.Marshaler.ContentType(v)
+}
+
+// Marshal marshals "v" by returning the body bytes if v is a
+// google.api.HttpBody message, otherwise it falls back to the default Marshaler.
+func (h *HTTPBodyMarshaler) Marshal(v interface{}) ([]byte, error) {
+	if httpBody, ok := v.(*httpbody.HttpBody); ok {
+		return httpBody.Data, nil
+	}
+	return h.Marshaler.Marshal(v)
+}