map.put(keyOne, valueOne);
        ReferenceEntry<Object, Object> entry = segment.getEntry(keyOne, hashOne);

        @SuppressWarnings("unchecked")
        Reference<Object> reference = (Reference<Object>) entry;
        reference.enqueue();

        map.put(keyTwo, valueTwo);
        assertFalse(map.containsKey(keyOne));
        assertFalse(map.containsValue(valueOne));

        map.put(keyOne, valueOne);
        ReferenceEntry<Object, Object> entry = segment.getEntry(keyOne, hashOne);

        @SuppressWarnings("unchecked")
        Reference<Object> reference = (Reference<Object>) entry;
        reference.enqueue();

        map.put(keyTwo, valueTwo);
        assertFalse(map.containsKey(keyOne));
        assertFalse(map.containsValue(valueOne));

    /**
     * Returns the entry associated with this value reference, or {@code null} if this value
     * reference is independent of any entry.
     */
    @CheckForNull
    ReferenceEntry<K, V> getEntry();

    /**
     * Creates a copy of this reference for the given entry.
     *
     * <p>{@code value} may be null only for a loading reference.
     */
    ValueReference<K, V> copyFor(

    /**
     * Returns the entry associated with this value reference, or {@code null} if this value
     * reference is independent of any entry.
     */
    @CheckForNull
    ReferenceEntry<K, V> getEntry();

    /**
     * Creates a copy of this reference for the given entry.
     *
     * <p>{@code value} may be null only for a loading reference.
     */
    ValueReference<K, V> copyFor(

    future2 = null;

    /*
     * Futures should be collected even if combiner never runs. This is kind of a silly test, since
     * the combiner is almost certain to hold its own reference to the futures, and a real app would
     * hold a reference to the executor and thus to the combiner. What we really care about is that
     * the futures are released once the combiner is done running. But we happen to provide this

    future2 = null;

    /*
     * Futures should be collected even if combiner never runs. This is kind of a silly test, since
     * the combiner is almost certain to hold its own reference to the futures, and a real app would
     * hold a reference to the executor and thus to the combiner. What we really care about is that
     * the futures are released once the combiner is done running. But we happen to provide this

     * href="https://developer.android.com/sdk/api_diff/16/">API Level 16</a> is the first version
     * in which {@code Cursor} is {@code Closeable}. To support older versions, pass a wrapper
     * {@code Closeable} with a method reference like {@code cursor::close}.
     *
     * <p>Note that this method is still binary-compatible between flavors because the erasure of
     * its parameter type is {@code Object}, not {@code AutoCloseable} or {@code Closeable}.

      TreeMap<K, V> newTreeMap(@CheckForNull Comparator<C> comparator) {
    // Ideally, the extra type parameter "C" shouldn't be necessary. It is a
    // work-around of a compiler type inference quirk that prevents the
    // following code from being compiled:
    // Comparator<Class<?>> comparator = null;
    // Map<Class<? extends Throwable>, String> map = newTreeMap(comparator);