`Unsafe::storeFence` and `VarHandle::releaseFence` were added in JDK 8 and 9 respectively; `MutableCallSite` was implemented in JDK 7, 2 years before the Unsafe addition. We should move the MutableCallSite's `AtomicInteger.lazySet(0)` call to an explicit `UNSAFE.storeFence()` for consistency and clarity.