fix(issue#809) spliting query param by &

[otniel123]

Here I fixed the separation of query params by comma, instead, now it is separeted by ampersand (&).

[christophd]

Many thanks for your contribution! I think you need to adjust the tests, too because the logic has changed. I would also love to see some new unit test that reproduces the initial error reported in #809

Apart from that I have one question. Your fix solves the commas being part of the query params, right. What about additional & characters in the new solution? Would that just hit the same error as before but now with & characters in the query params? I guess we would need to use some URL escape/unescape logic so users can use encoded strings for reserved characters such as , or &