* future is {@linkplain Future#isDone() done}.
   *
   * <p>Prefer to create {@code ListenableFuture} instances with {@link SettableFuture}, {@link
   * MoreExecutors#listeningDecorator( java.util.concurrent.ExecutorService)}, {@link
   * ListenableFutureTask}, {@link AbstractFuture}, and other utilities over creating plain {@code
   * Future} instances to be upgraded to {@code ListenableFuture} after the fact.

import static com.google.common.util.concurrent.Futures.immediateFuture;
import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
import static com.google.common.util.concurrent.MoreExecutors.listeningDecorator;
import static com.google.common.util.concurrent.MoreExecutors.shutdownAndAwaitTermination;
import static com.google.common.util.concurrent.Uninterruptibles.awaitUninterruptibly;

import static com.google.common.collect.Maps.immutableEntry;
import static com.google.common.truth.Truth.assertThat;
import static com.google.common.util.concurrent.MoreExecutors.listeningDecorator;
import static java.lang.Math.max;
import static java.lang.Thread.State.WAITING;
import static java.util.concurrent.Executors.newSingleThreadExecutor;
import static java.util.concurrent.TimeUnit.MILLISECONDS;