Github user leventov commented on the issue:
https://github.com/apache/zookeeper/pull/490
@anmolnar see http://errorprone.info/docs/installation, the first
paragraph: "Please note that Error Prone must be run on JDK 8 or newer. It can
be used to build Java 6 or 7 code by setting the appropriate -source / -target
/ -bootclasspath flags."---
