@Test
  public void test_GatewaySenderIdAndAsyncEventId() {
    cache = new CacheFactory().set(MCAST_PORT, "0").create();
    RegionFactory factory = cache.createRegionFactory();
    factory.addGatewaySenderId("ln");
    factory.addGatewaySenderId("ny");
    factory.addAsyncEventQueueId("Async_LN");

    Set<String> senderIds = new HashSet<>();
    senderIds.add("ln");
    senderIds.add("ny");

    Region r = factory.create("Customer");
    assertEquals(senderIds, ((LocalRegion) r).getGatewaySenderIds());
  }
Test to validate that same gatewaySender Id can not be added to the region attributes.
geode-wan/src/integrationTest/java/org/apache/geode/internal/cache/wan/misc/WANConfigurationJUnitTest.java