message1.setCorrelationId(message1.getUniqueId());
message2.setCorrelationId(message1.getUniqueId());
message3.setCorrelationId(message1.getUniqueId());
message1.setCorrelationGroupSize(3);
InboundEndpoint endpoint = MuleTestUtils.getTestInboundEndpoint(MessageExchangePattern.ONE_WAY, muleContext);
MuleEvent event1 = new DefaultMuleEvent(message1, endpoint, session);
MuleEvent event2 = new DefaultMuleEvent(message2, endpoint, session);
MuleEvent event3 = new DefaultMuleEvent(message3, endpoint, session);
assertNull(router.process(event1));