@Test
  public void testContains() {
    CustomEntryConcurrentHashMap map = map5();
    assertTrue(map.contains("A"));
    assertFalse(map.contains("Z"));
  }
contains returns true for contained value
geode-core/src/integrationTest/java/org/apache/geode/internal/util/concurrent/cm/ConcurrentHashMapJUnitTest.java