import com.google.errorprone.annotations.CheckReturnValue;
import java.util.concurrent.AbstractExecutorService;
import java.util.concurrent.Callable;
import java.util.concurrent.RunnableFuture;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Abstract {@link ListeningExecutorService} implementation that creates {@link ListenableFuture}

import com.google.errorprone.annotations.CheckReturnValue;
import java.util.concurrent.AbstractExecutorService;
import java.util.concurrent.Callable;
import java.util.concurrent.RunnableFuture;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Abstract {@link ListeningExecutorService} implementation that creates {@link ListenableFuture}

    TestListeningExecutorService e = new TestListeningExecutorService();

    TestRunnable runnable = new TestRunnable();
    ListenableFuture<?> runnableFuture = e.submit(runnable);
    assertThat(runnableFuture).isInstanceOf(TrustedListenableFutureTask.class);
    assertTrue(runnableFuture.isDone());
    assertTrue(runnable.run);

    ListenableFuture<String> callableFuture = e.submit(new TestCallable());

    TestListeningExecutorService e = new TestListeningExecutorService();

    TestRunnable runnable = new TestRunnable();
    ListenableFuture<?> runnableFuture = e.submit(runnable);
    assertThat(runnableFuture).isInstanceOf(TrustedListenableFutureTask.class);
    assertTrue(runnableFuture.isDone());
    assertTrue(runnable.run);

    ListenableFuture<String> callableFuture = e.submit(new TestCallable());