MuleMessage message = new DefaultMuleMessage("data", muleContext);
MuleEvent event = new DefaultMuleEvent(message, MessageExchangePattern.ONE_WAY, getTestService());
event.getSession().setProperty("key", "value");
async.process(event);
asyncListener.latch.await(RECEIVE_TIMEOUT, TimeUnit.MILLISECONDS);
MuleEvent asyncEvent = asyncListener.event;
// Event is copied, but session isn't