assertThrows(IllegalArgumentException.class, () -> entry.setValue(5));

    assertEquals(ImmutableMap.of("a", 2, "b", 4), filtered);
  }

  public void testFilteredValuesClear() {
    Map<String, Integer> unfiltered = createUnfiltered();
    unfiltered.put("one", 1);
    unfiltered.put("two", 2);
    unfiltered.put("three", 3);
    unfiltered.put("four", 4);

    assertThrows(IllegalArgumentException.class, () -> entry.setValue(5));

    assertEquals(ImmutableMap.of("a", 2, "b", 4), filtered);
  }

  public void testFilteredValuesClear() {
    Map<String, Integer> unfiltered = createUnfiltered();
    unfiltered.put("one", 1);
    unfiltered.put("two", 2);
    unfiltered.put("three", 3);
    unfiltered.put("four", 4);