Entry<K, Collection<V>> entry = sortedMap().ceilingEntry(key);
      return (entry == null) ? null : wrapEntry(entry);
    }

    @Override
    public @Nullable K ceilingKey(@ParametricNullness K key) {
      return sortedMap().ceilingKey(key);
    }

    @Override
    public @Nullable Entry<K, Collection<V>> higherEntry(@ParametricNullness K key) {

      return standardFloorKey(key);
    }

    @Override
    public @Nullable Entry<K, V> ceilingEntry(K key) {
      return standardCeilingEntry(key);
    }

    @Override
    public @Nullable K ceilingKey(K key) {
      return standardCeilingKey(key);
    }

    @Override
    public @Nullable Entry<K, V> higherEntry(K key) {
      return standardHigherEntry(key);
    }

    @Override

    public @Nullable Entry<K, V2> ceilingEntry(@ParametricNullness K key) {
      return transformEntry(fromMap().ceilingEntry(key));
    }

    @Override
    public @Nullable K ceilingKey(@ParametricNullness K key) {
      return fromMap().ceilingKey(key);
    }

    @Override
    public NavigableSet<K> descendingKeySet() {
      return fromMap().descendingKeySet();
    }

    @Override

    assertEquals("three", map.higherKey("one"));
    assertEquals("three", map.higherKey("r"));
    assertEquals("three", map.ceilingKey("r"));
    assertEquals("one", map.ceilingKey("one"));
    assertEquals(mapEntry("three", 5), map.higherEntry("one"));
    assertEquals(mapEntry("one", 3), map.ceilingEntry("one"));
    assertEquals("one", map.lowerKey("three"));

    assertEquals("three", map.higherKey("one"));
    assertEquals("three", map.higherKey("r"));
    assertEquals("three", map.ceilingKey("r"));
    assertEquals("one", map.ceilingKey("one"));
    assertEquals(mapEntry("three", 5), map.higherEntry("one"));
    assertEquals(mapEntry("one", 3), map.ceilingEntry("one"));
    assertEquals("one", map.lowerKey("three"));