* cancelled. For details on when this is called, see {@link #collectOneValue}.
   */
  private void collectValueFromNonCancelledFuture(int index, Future<? extends InputT> future) {
    try {
      // We get the result, even if collectOneValue is a no-op, so that we can fail fast.
      // We use getUninterruptibly over getDone as a micro-optimization, we know the future is done.
      collectOneValue(index, getUninterruptibly(future));

    // Populate the results list with null initially.
    for (int i = 0; i < futures.size(); ++i) {
      values.add(null);
    }

    this.values = values;
  }

  @Override
  final void collectOneValue(int index, @ParametricNullness V returnValue) {
    @RetainedLocalRef List<@Nullable Present<V>> localValues = values;
    if (localValues != null) {
      localValues.set(index, new Present<>(returnValue));
    }
  }

    // Populate the results list with null initially.
    for (int i = 0; i < futures.size(); ++i) {
      values.add(null);
    }

    this.values = values;
  }

  @Override
  final void collectOneValue(int index, @ParametricNullness V returnValue) {
    @RetainedLocalRef List<@Nullable Present<V>> localValues = values;
    if (localValues != null) {
      localValues.set(index, new Present<>(returnValue));
    }
  }