ListenableFuture<? extends V>... futures) {
    ListenableFuture<List<@Nullable V>> nullable =
        new ListFuture<V>(ImmutableList.copyOf(futures), true);
    // allAsList ensures that it fills the output list with V instances.
    @SuppressWarnings("nullness")
    ListenableFuture<List<V>> nonNull = nullable;
    return nonNull;
  }

  /**

    internal var connectTimeout = 10_000
    internal var readTimeout = 10_000
    internal var writeTimeout = 10_000
    internal var pingInterval = 0
    internal var webSocketCloseTimeout = RealWebSocket.CANCEL_AFTER_CLOSE_MILLIS.toInt()
    internal var minWebSocketMessageToCompress = RealWebSocket.DEFAULT_MINIMUM_DEFLATE_SIZE
    internal var routeDatabase: RouteDatabase? = null
    internal var taskRunner: TaskRunner? = null