@Test
  public void testReplicatedSerialPropagationWithRemoteSenderConfiguredButNotStarted() {
    Integer lnPort = vm0.invoke(() -> WANTestBase.createFirstLocatorWithDSId(1));
    Integer nyPort = vm1.invoke(() -> WANTestBase.createFirstRemoteLocator(2, lnPort));

    createCacheInVMs(nyPort, vm2, vm3);
    createReceiverInVMs(vm2, vm3);

    createCacheInVMs(lnPort, vm4, vm5, vm6, vm7);
    createReceiverInVMs(vm4, vm5);

    vm4.invoke(() -> WANTestBase.createSender("ln", 2, false, 100, 10, false, false, null, true));
    vm5.invoke(() -> WANTestBase.createSender("ln", 2, false, 100, 10, false, false, null, true));

    startSenderInVMs("ln", vm4, vm5);

    vm4.invoke(createReplicatedRegionRunnable());
    vm5.invoke(createReplicatedRegionRunnable());
    vm6.invoke(createReplicatedRegionRunnable());
    vm7.invoke(createReplicatedRegionRunnable());

    vm2.invoke(() -> WANTestBase.createSender("ny", 1, false, 100, 10, false, false, null, true));
    vm3.invoke(() -> WANTestBase.createSender("ny", 1, false, 100, 10, false, false, null, true));

    vm2.invoke(
        () -> WANTestBase.createReplicatedRegion(getUniqueName() + "_RR", "ny", isOffHeap()));
    vm3.invoke(
        () -> WANTestBase.createReplicatedRegion(getUniqueName() + "_RR", "ny", isOffHeap()));

    vm4.invoke(() -> WANTestBase.doPuts(getUniqueName() + "_RR", 1000));

    startSenderInVMs("ny", vm2, vm3);

    vm2.invoke(() -> WANTestBase.validateRegionSize(getUniqueName() + "_RR", 1000));
    vm3.invoke(() -> WANTestBase.validateRegionSize(getUniqueName() + "_RR", 1000));
  }
Added for defect #48582 NPE when WAN sender configured but not started. All to all topology
with 2 WAN sites: Site 1 (LN site): vm4, vm5, vm6, vm7 Site 2 (NY site): vm2, vm3
geode-wan/src/distributedTest/java/org/apache/geode/internal/cache/wan/serial/SerialWANPropagationDUnitTest.java