Database internal lock timeouts do not return exceptions on the executeUpdate of a jdbc Statement object

Steps to reproduce:

1. create two Xids (xid1, xid2) with the same gtrid value and different branchqualifiers
2. conn1 = get XA connection
3. xaResource1 = conn1.getXAResource()
4. xaResource1.start(xid1,XAResource.TMNOFLAGS)
5. update row X via conn1 (using a Statement.executeUpdate call)
6. xaResource2 = conn2.getXAResource()
7. xaResource2.start(xid2,XAResource.TMNOFLAGS)
8. update row X via conn2
9. check the value of X via conn1

Observed behavior: step 8 hangs for a while (I assume it blocks on a lock and times out) and step 9 returns the value from before step 5 - i.e., the unchanged, original value.

The only hypothesis I find consistent with this is the following:

-step 8 blocks and returns after the transactions are rolled back (and the locks released)
-step 9 then returns the value after rollback, i.e. the original value

If this is the case, then step 8 should not return OK but rather throw an SQLException