+ gets lost when requesting login with oAuth2

[HanaGemela]

Server: 10.4.0 RC3
Client: 2.6.1 (build 13096)

Steps to recreate:

1. Install oAuth2 on the server
2. Add a new account with username name+2@test.com in the client
3. Log out
4. Log in

Actual result: Client requests login for name 2@test.com -> not possible to login
Expected result: Client requests login for name+2@test.com

Found when testing owncloud/core#36613

[ogoffart]

We use QUrlQuery to encode all our fields (in OAuth::authorisationLink)
+ normaly does not need to be encoded. The documentation of QUrlQuery has a documentation about that: https://doc.qt.io/qt-5/qurlquery.html#handling-of-spaces-and-plus
But QUrlQuery does not seem to allow to force the percent-encoding of +

The owncloud server understands an unencoded + as a space, which i think is a server bug.

We could workaround the problem by doing a search and replace of + with %2B in the query.

[michaelstingl]

The owncloud server understands an unencoded + as a space, which i think is a server bug.

Open issue?

[jnweiger]

A '+' (plus) is well known but historic url-encoding for a ' ' (whitespace). A raw plus character should always be percent-encoded, to avoid confusion.

https://de.wikipedia.org/wiki/URL-Encoding mentions that form-url-encoding differs from normal url-encoding because of the use of '+'. I disagree.

[michaelstingl]

fixed in #7771