StampedLocks have been talked about extensively at least on jsr-166 mailing list and they required adding load/load barrier in sun.misc.Unsafe. That was the prime reason it needed Java 8, as previously it required a no-op CAS on the load path.

For most people StampedLock will remain quite a mystery as they are harder to use and the vact majority of Java developers doesn't actually write (or even use) low-level concurrency primitives.