for (K key : keysToTest) {
      assertEquals(expected.lowerEntry(key), navigableMap.lowerEntry(key));
      assertEquals(expected.floorEntry(key), navigableMap.floorEntry(key));
      assertEquals(expected.ceilingEntry(key), navigableMap.ceilingEntry(key));
      assertEquals(expected.higherEntry(key), navigableMap.higherEntry(key));

      return standardLowerEntry(key);
    }

    @Override
    public @Nullable K lowerKey(K key) {
      return standardLowerKey(key);
    }

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

    @Override
    public @Nullable K floorKey(K key) {
      return standardFloorKey(key);
    }

    @Override

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

    @Override
    public @Nullable Entry<K, Collection<V>> floorEntry(@ParametricNullness K key) {
      Entry<K, Collection<V>> entry = sortedMap().floorEntry(key);
      return (entry == null) ? null : wrapEntry(entry);
    }

    @Override
    public @Nullable K floorKey(@ParametricNullness K key) {

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

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

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

    @Override

    }
    {
      Entry<Integer, String> entry = unmod.lowerEntry(1);
      assertThat(entry).isNull();
    }
    {
      Entry<Integer, String> entry = unmod.floorEntry(2);
      assertThrows(UnsupportedOperationException.class, () -> entry.setValue("four"));
    }
    {
      Entry<Integer, String> entry = unmod.ceilingEntry(2);

    }
    {
      Entry<Integer, String> entry = unmod.lowerEntry(1);
      assertThat(entry).isNull();
    }
    {
      Entry<Integer, String> entry = unmod.floorEntry(2);
      assertThrows(UnsupportedOperationException.class, () -> entry.setValue("four"));
    }
    {
      Entry<Integer, String> entry = unmod.ceilingEntry(2);