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

    }
    {
      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);