How to suppress a Heartbeat resource from starting in failover data center?
I think, you can't do it with (native) heartbeat only. You can use pacemaker, he can work with quorums, but... You don't have a quorum. Imagine, that link between data centers fails - every of east and west will think, he is only one survivor and every of them start application, switch mysql to master mode etc. And you'll get really split-brain position.
IMHO, if you need really HA, you need 3th data center, then migrate MySQL to MariaDB with Galera cluster, and start on them your Java app, may be even in active-active-active mode.