@Override
        public void beforeUpdate(EntryEvent<String, String> event) {
          EntryEventImpl copy = new EntryEventImpl((EntryEventImpl) event);
          copy.copyOffHeapToHeap();
          WRITER_QUEUE.add(copy);
        }
A CacheWriter that simply stores received events in a queue for evaluation.
geode-core/src/distributedTest/java/org/apache/geode/internal/compression/CompressionCacheListenerDUnitTest.java