@Test
  public void testPutIfAbsent() {
    CopyOnWriteHashMap map = map5();
    map.putIfAbsent(six, "Z");
    assertTrue(map.containsKey(six));
  }
putIfAbsent works when the given key is not present
geode-core/src/integrationTest/java/org/apache/geode/internal/util/concurrent/CopyOnWriteHashMapJUnitTest.java