jgit, MutableInteger vs AtomicInteger

Hi,

I've just started browsing jgit sources and an obvious question arise. I didn't found such question in mail list and decided to ask the community.

I don't see reason behind creating own mutable integer container because we 
have java.util.concurrent.atomic.AtomicInteger with methods
    public final int get()
    public final void set(int i)

And that is what we want.

Regards,
  V. V.