Implement grpc-gateway Delimited interface

Implement the Delimited interface for the gogo/protobuf JSONPb marshaller.

Fixes #20925

Gopkg.toml

@@ -47,7 +47,7 @@ ignored = [
   name = "github.com/go-sql-driver/mysql"
   branch = "master"
 
-# https://github.com/grpc-ecosystem/grpc-gateway/commit/893772d
+# https://github.com/grpc-ecosystem/grpc-gateway/commit/8db8c1a
 [[constraint]]
   name = "github.com/grpc-ecosystem/grpc-gateway"
   branch = "master"

pkg/util/protoutil/jsonpb_marshal.go

@@ -133,3 +133,10 @@ func (j *JSONPb) NewEncoder(w io.Writer) gwruntime.Encoder {
 		return errors.Errorf("unexpected type %T does not implement %s", v, typeProtoMessage)
 	})
 }
+
+var _ gwruntime.Delimited = (*JSONPb)(nil)
+
+// Delimiter implements gwruntime.Delimited.
+func (*JSONPb) Delimiter() []byte {
+	return []byte("\n")
+}

pkg/util/protoutil/marshaler.go

@@ -101,3 +101,10 @@ func (e *protoEncoder) Encode(v interface{}) error {
 	}
 	return errors.Errorf("unexpected type %T does not implement %s", v, typeProtoMessage)
 }
+
+var _ gwruntime.Delimited = (*ProtoPb)(nil)
+
+// Delimiter implements gwruntime.Delimited.
+func (*ProtoPb) Delimiter() []byte {
+	return nil
+}