Replace multus code with NPWG client library code

vendor/github.com/json-iterator/go/reflect_map.go

@@ -39,7 +39,11 @@ func encoderOfMap(ctx *ctx, typ reflect2.Type) ValEncoder {
 }
 
 func decoderOfMapKey(ctx *ctx, typ reflect2.Type) ValDecoder {
-	for _, extension := range ctx.extensions {
+	decoder := ctx.decoderExtension.CreateMapKeyDecoder(typ)
+	if decoder != nil {
+		return decoder
+	}
+	for _, extension := range ctx.extraExtensions {
 		decoder := extension.CreateMapKeyDecoder(typ)
 		if decoder != nil {
 			return decoder
@@ -60,14 +64,26 @@ func decoderOfMapKey(ctx *ctx, typ reflect2.Type) ValDecoder {
 		return &numericMapKeyDecoder{decoderOfType(ctx, typ)}
 	default:
 		ptrType := reflect2.PtrTo(typ)
-		if ptrType.Implements(textMarshalerType) {
+		if ptrType.Implements(unmarshalerType) {
+			return &referenceDecoder{
+				&unmarshalerDecoder{
+					valType: ptrType,
+				},
+			}
+		}
+		if typ.Implements(unmarshalerType) {
+			return &unmarshalerDecoder{
+				valType: typ,
+			}
+		}
+		if ptrType.Implements(textUnmarshalerType) {
 			return &referenceDecoder{
 				&textUnmarshalerDecoder{
 					valType: ptrType,
 				},
 			}
 		}
-		if typ.Implements(textMarshalerType) {
+		if typ.Implements(textUnmarshalerType) {
 			return &textUnmarshalerDecoder{
 				valType: typ,
 			}
@@ -77,7 +93,11 @@ func decoderOfMapKey(ctx *ctx, typ reflect2.Type) ValDecoder {
 }
 
 func encoderOfMapKey(ctx *ctx, typ reflect2.Type) ValEncoder {
-	for _, extension := range ctx.extensions {
+	encoder := ctx.encoderExtension.CreateMapKeyEncoder(typ)
+	if encoder != nil {
+		return encoder
+	}
+	for _, extension := range ctx.extraExtensions {
 		encoder := extension.CreateMapKeyEncoder(typ)
 		if encoder != nil {
 			return encoder
@@ -229,6 +249,10 @@ type mapEncoder struct {
 }
 
 func (encoder *mapEncoder) Encode(ptr unsafe.Pointer, stream *Stream) {
+	if *(*unsafe.Pointer)(ptr) == nil {
+		stream.WriteNil()
+		return
+	}
 	stream.WriteObjectStart()
 	iter := encoder.mapType.UnsafeIterate(ptr)
 	for i := 0; iter.HasNext(); i++ {