IdP fails to start after upgrading to Jetty12

[Cantor, Scott]

I can't really help you debug an IdP (see footer for why), but I'll correct a misconception you seem to have:

> I don’t really get how these warnings occur. Our MySQL Config
> uses HikariCP as the class, which should be loaded correctly. 

Hikari is a pooling driver, not the actual data source. You are self-evidently using MySQL as the underlying data source, it's just noting the driver class changed.

-- Scott