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

    Entry<String, Integer> entry = filtered.entrySet().iterator().next();
    try {
      entry.setValue(5);
      fail();
    } catch (IllegalArgumentException expected) {
    }

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

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

    Entry<String, Integer> entry = filtered.entrySet().iterator().next();
    try {
      entry.setValue(5);
      fail();
    } catch (IllegalArgumentException expected) {
    }

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