private void setArmHook(String rname) {
    LocalRegion r = (LocalRegion) cache.getRegion(rname);
    ArmLockHook theArmHook = new ArmLockHook();
    ((AbstractRegionMap) r.entries).setARMLockTestHook(theArmHook);
  }
Set the abstract region map lock hook to detect attempt to acquire write lock by region
operation.
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/ClearTXLockingDUnitTest.java