--- contrib/libs/protobuf/src/google/protobuf/json/internal/descriptor_traits.h	(2babb01d30e285a96044041b98053d9edbb48b2a)
+++ contrib/libs/protobuf/src/google/protobuf/json/internal/descriptor_traits.h	(aa368d72b2d33c8c4857d03624b10b97d2161d61)
@@ -232,6 +232,9 @@ struct Proto2Descriptor {
   static absl::string_view FieldJsonName(Field f) {
     return f->has_json_name() ? f->json_name() : f->camelcase_name();
   }
+  static bool HasJsonName(Field f) {
+    return f->has_json_name();
+  }
   static absl::string_view FieldFullName(Field f) { return f->full_name(); }
 
   static absl::string_view FieldTypeName(Field f) {
@@ -399,6 +402,9 @@ struct Proto3Type {
   static absl::string_view FieldJsonName(Field f) {
     return f->proto().json_name();
   }
+  static bool HasJsonName(Field f) {
+    return true;
+  }
   static absl::string_view FieldFullName(Field f) { return f->proto().name(); }
 
   static absl::string_view FieldTypeName(Field f) {
--- contrib/libs/protobuf/src/google/protobuf/json/internal/unparser.cc	(2babb01d30e285a96044041b98053d9edbb48b2a)
+++ contrib/libs/protobuf/src/google/protobuf/json/internal/unparser.cc	(aa368d72b2d33c8c4857d03624b10b97d2161d61)
@@ -399,7 +399,7 @@ absl::Status WriteField(JsonWriter& writer, const Msg<Traits>& msg,
     // with an uppercase letter, and the Json name does not, we uppercase it.
     absl::string_view original_name = Traits::FieldName(field);
     absl::string_view json_name = Traits::FieldJsonName(field);
-    if (writer.options().allow_legacy_syntax &&
+    if (writer.options().allow_legacy_syntax && !Traits::HasJsonName(field) &&
         absl::ascii_isupper(original_name[0]) &&
         !absl::ascii_isupper(json_name[0])) {
       writer.Write(MakeQuoted(absl::ascii_toupper(original_name[0]),