Method has_string_value

libapp2sys/prebuilt/include/google/protobuf/struct.pb.h:582–584

optional string string_value = 3;

// optional string string_value = 3;
inline bool Value::has_string_value() const {
  return kind_case() == kStringValue;
}
inline void Value::set_has_string_value() {
  _oneof_case_[0] = kStringValue;
}