}
  }

  /**
   * {@link Futures#allAsList(Iterable)} or {@link Futures#successfulAsList(Iterable)}, hidden
   * behind a common interface for testing.
   */
  @J2ktIncompatible
  @GwtIncompatible // used only in GwtIncompatible tests
  private interface Merger {

    ListenableFuture<List<String>> merged(ListenableFuture<String> a, ListenableFuture<String> b);

    Merger allMerger =

    }
  }

  /**
   * {@link Futures#allAsList(Iterable)} or {@link Futures#successfulAsList(Iterable)}, hidden
   * behind a common interface for testing.
   */
  @J2ktIncompatible
  @GwtIncompatible // used only in GwtIncompatible tests
  private interface Merger {

    ListenableFuture<List<String>> merged(ListenableFuture<String> a, ListenableFuture<String> b);

    Merger allMerger =

      connectWriteOrder(newEntry, original.getNextInWriteQueue());

      nullifyWriteOrder(original);
    }
  }

  /** A reference to a value. */
  interface ValueReference<K, V> {
    /** Returns the value. Does not block or throw exceptions. */
    @CheckForNull
    V get();

    /**

     * build</a>.)
     *
     * <p>Be careful when targeting an older SDK than you are building against (most commonly when
     * building for Android): Ensure that any object you pass implements the interface not just in
     * your current SDK version but also at the oldest version you support. For example, <a
     * href="https://developer.android.com/sdk/api_diff/16/">API Level 16</a> is the first version

      connectWriteOrder(newEntry, original.getNextInWriteQueue());

      nullifyWriteOrder(original);
    }
  }

  /** A reference to a value. */
  interface ValueReference<K, V> {
    /** Returns the value. Does not block or throw exceptions. */
    @CheckForNull
    V get();

    /**

   *
   * @param <K> the key type of the input and output entries
   * @param <V1> the value type of the input entry
   * @param <V2> the value type of the output entry
   * @since 7.0
   */
  public interface EntryTransformer<
      K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object> {
    /**
     * Determines an output value based on a key-value pair. This method is <i>generally