ceki/logback — comment on commit bd9ba34db189cfa1db3a3590a9bda4437736ceeb
File:  line 0
By huxi:

With the above code in place, it is possible to selectively grant Logback the privilege of accessing the ClassLoader but denying it to all other classes. Either that or I seriously misunderstand the whole concept.
It allows to alleviate the restrictions of trusted code (in this case: Logback) in an otherwise restricted environment. I guess that this is getting more and more important with respect to cloud computing or plugins for applications.
I'd agree to just delete it if it would make a significant difference in performance... but since it is very cheap (check against null) without a SecurityManager and "the right thing" to do if there is one in place, I'd just use the code above until we discover anything bad about it.