@Override
          public Object getRoutingObject(EntryOperation<String, Integer> opDetails) {
            return opDetails.getKey().substring(0, 3);
          }
This test class tests the communication pattern of a transaction for replicate and partition
region. There are five VMs that two CacheServers, CacheServer with Pool and two clients. The
communicate of a transaction is the following three patterns. In addition, this test class also
tests transactions from older version clients to check backwards compatibility.<br>
<ol>
<li>CacheServer (transaction)-> CacheServer</li>
<li>Client (transaction)-> CacheServer</li>
<li>Old version client (transaction)-> CacheServer</li>
<li>CacheServer via Pool (transaction)-> CacheServer</li>
</ol>
geode-core/src/upgradeTest/java/org/apache/geode/internal/cache/TxCommitMessageBCTestBase.java