Move semantics when serializing to json

[Numendacil]

Is it possible to define a custom to_json() that takes a rvalue reference of given object to avoid unnecessary copy when dealing with large string values? For example

using json = nlohmann::json;
struct Data
{
	std::string buffer;
};

void to_json(json& j, const Data& p)
{
	j = p.buffer;
}

void to_json(json& j, Data&& p)
{
	j = std::move(p.buffer);
}

int main
{
	Data d{"some large base64 str"};
	json j;
	j = d;	// call to_json(json&, const Data&)
	j = std::move(d);	// call to_json(json&, Data&&)
}

Have given try for the above code i found that it actually works, but is seemly undocumented, so I'm asking if this is the desired behavior, and also if similar mechanisms exist in from_json also

[Numendacil]

Seems that using void to_json(json& j, Data p) is sufficient (instead of writing two versions)