Problem with SAX handler class after upgrade from 3.7.3 to 3.8.0

[BartVandewoestyne]

After an upgrade from 3.7.3 to 3.8.0, our code currently fails to build with the error that it cannot instantiate our SaxEventConsumer class, because it apparently now is abstract. Following the SAX interface documentation at https://github.com/nlohmann/json#serialization--deserialization we derive from json::json_sax_t

class SaxEventConsumer : public json::json_sax_t

and we implement all the interface functions mentioned in the documentation link above. Still, Visual Studio 2019 gives me

ICJSONUtils.cpp(30): error C2259: 'SaxEventConsumer': cannot instantiate abstract class
 ICJSONUtils.cpp(30): note: due to following members:
 ICJSONUtils.cpp(30): note: 'bool nlohmann::json_sax<nlohmann::basic_json<std::map,std::vector,std::string,bool,int64_t,uint64_t,double,std::allocator,nlohmann::adl_serializer,std::vector<uint8_t,std::allocator<_Ty>>>>::binary(nlohmann::byte_container_with_subtype<BinaryType> &)': is abstract
         with
         [
             _Ty=uint8_t,
             BinaryType=std::vector<uint8_t,std::allocator<uint8_t>>
         ]
D:\SVN\foo\bar\ThirdParty\json\custom\single_include\nlohmann/json.hpp(4962): note: see declaration of 'nlohmann::json_sax<nlohmann::basic_json<std::map,std::vector,std::string,bool,int64_t,uint64_t,double,std::allocator,nlohmann::adl_serializer,std::vector<uint8_t,std::allocator<_Ty>>>>::binary'
         with
         [
             _Ty=uint8_t
         ]

and I don't understand why. Are there other interface functions to implement? Why is our SaxEventConsumer class still abstract?

[BartVandewoestyne]

OK, I think I solved my problem: it appears there is also a bool binary(binary_t& val) virtual function to implement in the 3.8.0 version, which isn't there in the 3.7.3 version. After implementing that one, things now compile.