for (int i = 0; i < 10; i++) {
          assertEquals(unfiltered.lower(i), filtered.lower(i));
          assertEquals(unfiltered.floor(i), filtered.floor(i));
          assertEquals(unfiltered.ceiling(i), filtered.ceiling(i));
          assertEquals(unfiltered.higher(i), filtered.higher(i));
        }
      }
    }
  }

  private FilteredCollectionsTestUtil() {}

    final Collection<E> unfiltered;
    final Predicate<? super E> predicate;

    FilteredCollection(Collection<E> unfiltered, Predicate<? super E> predicate) {
      this.unfiltered = unfiltered;
      this.predicate = predicate;
    }

    FilteredCollection<E> createCombined(Predicate<? super E> newPredicate) {
      return new FilteredCollection<>(unfiltered, Predicates.and(predicate, newPredicate));
    }

                List<String> unfiltered = newArrayList();
                unfiltered.add("yyy");
                unfiltered.addAll(ImmutableList.copyOf(elements));
                unfiltered.add("zzz");
                unfiltered.add("abc");
                return Collections2.filter(Collections2.filter(unfiltered, LENGTH_1), NOT_YYY_ZZZ);
              }
            })

                List<String> unfiltered = newArrayList();
                unfiltered.add("yyy");
                unfiltered.addAll(ImmutableList.copyOf(elements));
                unfiltered.add("zzz");
                unfiltered.add("abc");
                return Collections2.filter(Collections2.filter(unfiltered, LENGTH_1), NOT_YYY_ZZZ);
              }
            })

        for (int i = 0; i < 10; i++) {
          assertEquals(unfiltered.lower(i), filtered.lower(i));
          assertEquals(unfiltered.floor(i), filtered.floor(i));
          assertEquals(unfiltered.ceiling(i), filtered.ceiling(i));
          assertEquals(unfiltered.higher(i), filtered.higher(i));
        }
      }
    }
  }

  private FilteredCollectionsTestUtil() {}

    final Collection<E> unfiltered;
    final Predicate<? super E> predicate;

    FilteredCollection(Collection<E> unfiltered, Predicate<? super E> predicate) {
      this.unfiltered = unfiltered;
      this.predicate = predicate;
    }

    FilteredCollection<E> createCombined(Predicate<? super E> newPredicate) {
      return new FilteredCollection<>(unfiltered, Predicates.and(predicate, newPredicate));
    }

    }
    return new FilteredMultiset<>(unfiltered, predicate);
  }

  private static final class FilteredMultiset<E extends @Nullable Object> extends ViewMultiset<E> {
    final Multiset<E> unfiltered;
    final Predicate<? super E> predicate;

    FilteredMultiset(Multiset<E> unfiltered, Predicate<? super E> predicate) {
      this.unfiltered = checkNotNull(unfiltered);

  final Multimap<K, V> unfiltered;
  final Predicate<? super Entry<K, V>> predicate;

  FilteredEntryMultimap(Multimap<K, V> unfiltered, Predicate<? super Entry<K, V>> predicate) {
    this.unfiltered = checkNotNull(unfiltered);
    this.predicate = checkNotNull(predicate);
  }

  @Override
  public Multimap<K, V> unfiltered() {
    return unfiltered;
  }

  @Override

                Set<String> unfiltered = Sets.newLinkedHashSet();
                unfiltered.add("yyy");
                unfiltered.addAll(ImmutableList.copyOf(elements));
                unfiltered.add("zzz");
                unfiltered.add("abc");
                return Sets.filter(
                    Sets.filter(unfiltered, Collections2Test.LENGTH_1),

    checkNotNull(retainIfTrue);
    return new FluentIterable<T>() {
      @Override
      public Iterator<T> iterator() {
        return Iterators.filter(unfiltered.iterator(), retainIfTrue);
      }

      @Override
      public void forEach(Consumer<? super T> action) {
        checkNotNull(action);
        unfiltered.forEach(
            (@ParametricNullness T a) -> {
              if (retainIfTrue.test(a)) {