Cassandra support for JDK 9

Hi,

I tried to compile Cassandra with JDK 9 and ran into compilation issues because monitorEnter/monitorExit functions have been removed from sun.misc.Unsafe in JDK9 (http://mail.openjdk.java.net/pipermail/jdk9-hs-rt-changes/2015-January/000773.html).

Is there a specific reason why Cassandra uses these Unsafe APIs instead of say java.util.concurrent.locks?

Thanks,
shylaja