jsonpb: Honor EmitDefaults for nilable types

jsonpb/jsonpb.go

@@ -178,16 +178,13 @@ func (m *Marshaler) marshalObject(out *errWriter, v proto.Message, indent, typeU
 			continue
 		}
 
-		// IsNil will panic on most value kinds.
-		switch value.Kind() {
-		case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
-			if value.IsNil() {
-				continue
-			}
-		}
-
 		if !m.EmitDefaults {
 			switch value.Kind() {
+			// IsNil will panic on most value kinds.
+			case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
+				if value.IsNil() {
+					continue
+				}
 			case reflect.Bool:
 				if !value.Bool() {
 					continue

jsonpb/jsonpb_test.go

@@ -350,6 +350,7 @@ var marshalingTests = []struct {
 		`{"rFunny":[1,2]}`},
 	{"empty value", marshaler, &pb.Simple3{}, `{}`},
 	{"empty value emitted", Marshaler{EmitDefaults: true}, &pb.Simple3{}, `{"dub":0}`},
+	{"empty value emitted", Marshaler{EmitDefaults: true}, &pb.Slicy{}, `{"slicy":[]}`},
 	{"map<int64, int32>", marshaler, &pb.Mappy{Nummy: map[int64]int32{1: 2, 3: 4}}, `{"nummy":{"1":2,"3":4}}`},
 	{"map<int64, int32>", marshalerAllOptions, &pb.Mappy{Nummy: map[int64]int32{1: 2, 3: 4}}, nummyPrettyJSON},
 	{"map<string, string>", marshaler,

jsonpb/jsonpb_test_proto/more_test_objects.proto

@@ -55,3 +55,7 @@ message Mappy {
   map<uint32, bool> u32booly = 9;
   map<uint64, bool> u64booly = 10;
 }
+
+message Slicy {
+  repeated string slicy = 1;
+}