XSS API is using other JSR-305 annotations than the rest of Sling

According to https://sling.apache.org/documentation/development/jsr-305.html only two different annotations are supposed to be used:

javax.annotation.CheckForNull
javax.annotation.Nonnull

The XSSAPI uses though

javax.annotation.Nullable
javax.annotation.Nonnull

Since it is trickier to setup the IDE to support both Nullable and CheckForNull and also FindBugs is only supporting the latter, I would recommend to switch to CheckForNull for return values which might be null. Every method argument which is not explicitly marked as Nonnull is always considered Nullable by every tool!