An old fix:

https://github.com/openjdk/jdk/commit/21312c5617160ee294acedd0636e3e52d607fce8

Caused Sun API warnings to be emitted using `Log::mandatoryWarning`. This was done to make sure that all warnings went through `Log::report`, while ensuring that such warnings could not be suppressed e.g. with `nowarn`.

Unfortunately this change also resulted in upgrading these warnings to the status of "mandatory warning" -- meaning a warning that is mandated by the JLS -- which is clearly not the case here. This bad status can be seen when interacting with diagnostic objects using the compiler API.