@Override
    void validate(EntryEvent event) {
      if (!event.getOperation().isCreate()) {
        fail("expected only create events");
      }
      numCreates.incrementAndGet();
    }
tests for the concurrentMapOperations. there are more tests in ClientServerMiscDUnitTest
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/ConcurrentMapOpsDUnitTest.java