`TokenBuffer`does not implement `writeString(Reader reader, int len)`

[kilink]

Describe the bug

Calling the writeString method on JsonGenerator that accepts a Reader throws when the underlying implementation is TokenBuffer. This happens for instance one when calls convertValue, but makes it awkward for the Serializer to be agnostic to whether it's being called for conversion or serialization.

Version information
Which Jackson version(s) was this for?

2.14.x

To Reproduce

Here's a contrived example:

@JsonSerialize(using = Foo.Serializer.class)
class Foo {
    static class Serializer extends StdSerializer<Foo> {
        Serializer() {
            super(Foo.class);
        }

        @Override
        public void serialize(Foo value, JsonGenerator gen, SerializerProvider provider) throws IOException {
            gen.writeStartObject();
            gen.writeFieldName("field");
            gen.writeString(new StringReader("foobar"), 6);
            gen.writeEndObject();
        }
    }
}

ObjectMapper mapper = new ObjectMapper();
Foo obj = new Foo();
// works
String serialized = mapper.writeValueAsString(obj);
// fails
Map<String, String> map = mapper.convertValue(obj, new TypeReference<Map<String, String>>() {});

[cowtowncoder]

Interesting. Ok, yes, sounds like a missing piece to implement.