{new MapRetrievalCache<String, String>(new TreeMap<String, String>(nullsLast))}
        });
  }

  @Before
  public void init() {
    mapCache.clear();
  }

  @Test
  public void testKeySetIterator() {
    mapCache.put("A", "A_value");
    mapCache.put("B", "B_value");
    mapCache.put("C", "C_value");

    assertThat(mapCache.unmodifiableKeySet()).hasSize(3);