import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A {@link RunnableFuture} that also implements the {@link ListenableFuture} interface.
 *
 * <p>This should be used in preference to {@link ListenableFutureTask} when possible for
 * performance reasons.
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault