@Test
  public void testContainsKey() {
    CustomEntryConcurrentHashMap map = map5();
    assertTrue(map.containsKey(one));
    assertFalse(map.containsKey(zero));
  }
containsKey returns true for contained key
geode-core/src/integrationTest/java/org/apache/geode/internal/util/concurrent/cm/ConcurrentHashMapJUnitTest.java