Possible wrong encoding/decoding of OAuth2 authorization code.

Issue may happen when QOAuth2AuthorizationCodeFlow receives OAuth2 authorization code and sends it back to get token.

When QOAuthHttpServerReplyHandlerPrivate decodes OAuth2 authorization code from QUrlQuery with QUrl::ComponentFormattingOption::PrettyDecoded flags (QOAuthHttpServerReplyHandlerPrivate::_q_answerClient()).

However QOAuth2AuthorizationCodeFlow encodes same authorization code into QUrlQuery using QUrl::ComponentFormattingOption::FullyEncoded flags (QOAuth2AuthorizationCodeFlow::requestAccessToken()). Maybe it can lead to corruption of authorization code.

In my case if authorization code contains '/' symbol it will be encoded by OAuth2 server as '%2F' and will not be decoded inside QOAuthHttpServerReplyHandlerPrivate::_q_answerClient(). So it becomes '%252F' when encodes back and OAuth2 server will reject such authorisation code.