private void doRemoveTest(RegionShortcut serverShortcut, ClientRegionShortcut clientShortcut,
      boolean serverConcChecks, boolean clientConcChecks) {
    setupGemFireCacheServer(serverShortcut, serverConcChecks);
    setupGemFireClientCache(clientShortcut, clientConcChecks);
    clientVM.invoke(() -> {
      getBlackboard().setMailbox(BB_MAILBOX_KEY, "");
      Region<String, String> aRegion = ClientCacheFactory.getAnyInstance().getRegion(REGION_NAME);
      Object returnedValue = aRegion.remove(NON_EXISTENT_KEY);
      assertNull(returnedValue);
      Object error = getBlackboard().getMailbox(BB_MAILBOX_KEY);
      assertNotNull(error);
      assertEquals("", error);
    });
  }
Add values to a region, then do a removeAll using both existent and non-existent keys. If a
listener event is invoked on a non-existent key, the listener writes it to the blackboard. Read
from the blackboard and fail the test if a listener event was invoked for a non-existent key.
geode-core/src/distributedTest/java/org/apache/geode/cache/client/RemoveAllCacheListenerClientServerRegressionTest.java