private void registerInterestOneKey(VM vm, final String key) {
    vm.invoke(new SerializableRunnable("register interest in " + key) {
      @Override
      public void run() {
        TestRegion.registerInterest(key);
      }
    });
  }
test that clients receive tombstones in register-interest results
geode-core/src/distributedTest/java/org/apache/geode/cache30/ClientServerCCEDUnitTest.java