If environment variables are configured like this MY_VAR="", then the quotation marks might be literally parsed, so that user.equals("\"\"") --> true and user.isBlank() --> false.
This problem might be dependent on the operating system and was reproduced so far only on Windows 11.
In the current code structure only 'isBlank()' is checked, which leads to oauth configuration with an invalid uri "", which in turn causes an error to be thrown.

This can be fixed by additinally checking with escape characters if user.equals("\"\"").