final TransactionRunner runner = new TransactionRunner(env);
runner.setAllowNestedTransactions(DbCompat.NESTED_TRANSACTIONS);
assertNull(currentTxn.getTransaction());
runner.run(new TransactionWorker() {
public void doWork() throws Exception {
final Transaction txn1 = currentTxn.getTransaction();
assertNotNull(txn1);
assertNull(map.put(ONE, ONE));
assertEquals(ONE, map.get(ONE));