m = (TextMessage)consumer.receive(100);
assertNull(m);
m = (TextMessage)consumer.receive(700);
assertNotNull(m);
assertEquals("1st", m.getText());
session.rollback();
// The message gets redelivered after 500 ms every time since
// we are not using exponential backoff.
m = (TextMessage)consumer.receive(100);
assertNull(m);