Object getValueOnDisk(Region region) throws EntryNotFoundException {
    ((LocalRegion) region).getDiskRegion().forceFlush();
    return ((LocalRegion) region).getValueOnDisk("Key");
  }
A region close is done after flush is over. The close is done in a separate thread and a 3000
ms wait is put to ensure that the separate thread has closed the region
geode-core/src/integrationTest/java/org/apache/geode/internal/cache/ConcurrentFlushingAndRegionOperationsJUnitTest.java