/**
   * Returns the backing delegate instance that methods are forwarded to. Abstract subclasses
   * generally override this method with an abstract method that has a more specific return type,
   * such as {@link ForwardingSet#delegate}. Concrete subclasses override this method to supply the
   * instance being decorated.
   */
  protected abstract Object delegate();

    return (key == null) ? null : Maps.safeGet(delegate, key);
  }

  @Override
  ImmutableSet<Entry<K, V>> createEntrySet() {
    return ImmutableSet.unsafeDelegate(
        new ForwardingSet<Entry<K, V>>() {
          @Override
          protected Set<Entry<K, V>> delegate() {
            return delegate.entrySet();
          }

          @Override

    } else {
      return new AddRejectingList<>(key);
    }
  }

  private static final class AddRejectingSet<K extends @Nullable Object, V extends @Nullable Object>
      extends ForwardingSet<V> {
    @ParametricNullness final K key;

    AddRejectingSet(@ParametricNullness K key) {
      this.key = key;
    }

    @Override
    public boolean add(@ParametricNullness V element) {

 * one to preserve compatibility.
 */
@SuppressWarnings("JdkObsolete")
public abstract class ForwardingSortedSet<E extends @Nullable Object> extends ForwardingSet<E>
    implements SortedSet<E> {

  /** Constructor for use by subclasses. */
  protected ForwardingSortedSet() {}

  @Override
  protected abstract SortedSet<E> delegate();

  @Override

        cast(getKey(), value);
        return super.setValue(value);
      }
    };
  }

  @Override
  public Set<Entry<Class<? extends @NonNull B>, B>> entrySet() {
    return new ForwardingSet<Entry<Class<? extends @NonNull B>, B>>() {

      @Override
      protected Set<Entry<Class<? extends @NonNull B>, B>> delegate() {
        return MutableClassToInstanceMap.this.delegate().entrySet();
      }

                      @Override
                      public Set<Entry<String>> entrySet() {
                        Set<Entry<String>> backingSet = super.entrySet();
                        return new ForwardingSet<Entry<String>>() {
                          @Override
                          protected Set<Entry<String>> delegate() {
                            return backingSet;
                          }

              .that(immutableCopy)
              .isIn(distinctCandidatesByAscendingSize);
        }
      }
    }
  }

  private static final class MutatedOnQuerySet<E> extends ForwardingSet<E> {
    final Iterator<ImmutableSet<E>> infiniteCandidates;

    MutatedOnQuerySet(Iterable<ImmutableSet<E>> infiniteCandidates) {
      this.infiniteCandidates = infiniteCandidates.iterator();
    }

          return true;
        }
      }
    }
    return false;
  }

  // Views

  @Override
  Set<E> createElementSet() {
    Set<E> delegate = countMap.keySet();
    return new ForwardingSet<E>() {
      @Override
      protected Set<E> delegate() {
        return delegate;
      }

      @Override
      public boolean contains(@Nullable Object object) {

    CountingSupplier<Set<Integer>> factory =
        new SetSupplier() {
          @Override
          public Set<Integer> getImpl() {
            Set<Integer> backing = super.getImpl();
            return new ForwardingSet<Integer>() {
              @Override
              protected Set<Integer> delegate() {
                return backing;
              }

              @Override

    public NavigableMap<K, V> descendingMap() {
      return asMap(set.descendingSet(), function);
    }
  }

  private static <E extends @Nullable Object> Set<E> removeOnlySet(Set<E> set) {
    return new ForwardingSet<E>() {
      @Override
      protected Set<E> delegate() {
        return set;
      }

      @Override
      public boolean add(@ParametricNullness E element) {