I think you should change URI::RESERVED_QUERY from
const std::string URI::RESERVED_QUERY = "#";
to
const std::string URI::RESERVED_QUERY = "#/";

because if you call the function encode from outside you can set the served characters as you want, ut if you use the setQuery function it use the encode with RESERVED_QUERY query automatically, and if your query string has a / character will be changed, and probably you don't want