public void testDescendingMap() {
    NavigableMap<String, Integer> map = create();
    NavigableMap<String, Integer> descendingMap = map.descendingMap();
    assertTrue(descendingMap instanceof SynchronizedNavigableMap);
    assertThat(((SynchronizedNavigableMap<String, Integer>) descendingMap).mutex)
        .isSameInstanceAs(mutex);
  }

  public void testFirstEntry() {
    assertThat(create().firstEntry()).isNull();
  }

                NavigableMap<String, String> delegate = populate(new TreeMap<>(), entries);
                return Collections.synchronizedNavigableMap(delegate);
              }
            })
        .named("synchronizedNavigableMap/TreeMap, natural")
        .withFeatures(
            MapFeature.GENERAL_PURPOSE,
            MapFeature.ALLOWS_NULL_VALUES,

cpovirk <******@****.***> 1740000085 -0800