unfiltered.put("badkey", 1);
    return Multimaps.filterEntries(unfiltered, ENTRY_PREDICATE);
  }

  private static final Predicate<String> KEY_PREDICATE = key -> !Objects.equals(key, "badkey");

  public void testFilterKeys() {
    Multimap<String, Integer> unfiltered = HashMultimap.create();
    unfiltered.put("foo", 55556);
    unfiltered.put("badkey", 1);
    Multimap<String, Integer> filtered = filterKeys(unfiltered, KEY_PREDICATE);