@SuppressWarnings("unchecked")
  private static <L extends TransactionListener> L firstTransactionListenerFrom(
      CacheTransactionManager transactionManager) {
    TransactionListener[] listeners = transactionManager.getListeners();
    assertThat(listeners).describedAs("Listeners on transactionManager for transaction with id "
        + transactionManager.getTransactionId()).hasSize(1);
    return (L) listeners[0];
  }
a class for testing handling of concurrent delta operations
geode-dunit/src/main/java/org/apache/geode/cache30/MultiVMRegionTestCase.java