final void releaseWaiters() {}

  AbstractFutureState() {}

  static final Object NULL = new Object();

  static final LazyLogger log = new LazyLogger(AbstractFuture.class);

  static final boolean GENERATE_CANCELLATION_CAUSES = false;

  private volatile @Nullable Object value;

  private volatile @Nullable Listener listeners;

  static final boolean GENERATE_CANCELLATION_CAUSES;

  static {
    // System.getProperty may throw if the security policy does not permit access.
    boolean generateCancellationCauses;
    try {
      generateCancellationCauses =
          parseBoolean(System.getProperty("guava.concurrent.generate_cancellation_cause", "false"));
    } catch (SecurityException e) {

  private static final class Cancellation {
    // constants to use when GENERATE_CANCELLATION_CAUSES = false
    static final @Nullable Cancellation CAUSELESS_INTERRUPTED;
    static final @Nullable Cancellation CAUSELESS_CANCELLED;

    static {
      if (GENERATE_CANCELLATION_CAUSES) {
        CAUSELESS_CANCELLED = null;
        CAUSELESS_INTERRUPTED = null;
      } else {

    // cause system property.  This allows us to run with both settings of the property in one jvm
    // without resorting to even crazier hacks to reset static final boolean fields.
    System.setProperty("guava.concurrent.generate_cancellation_cause", "true");
    String concurrentPackage = SettableFuture.class.getPackage().getName();
    classReloader =
        new URLClassLoader(ClassPathUtil.getClassPathUrls()) {
          @GuardedBy("loadedClasses")

    // cause system property.  This allows us to run with both settings of the property in one jvm
    // without resorting to even crazier hacks to reset static final boolean fields.
    System.setProperty("guava.concurrent.generate_cancellation_cause", "true");
    String concurrentPackage = SettableFuture.class.getPackage().getName();
    classReloader =
        new URLClassLoader(ClassPathUtil.getClassPathUrls()) {
          @GuardedBy("loadedClasses")

    }
  }

  static final class ImmediateCancelledFuture<V extends @Nullable Object> extends TrustedFuture<V> {
    static final @Nullable ImmediateCancelledFuture<Object> INSTANCE =
        AbstractFuture.GENERATE_CANCELLATION_CAUSES ? null : new ImmediateCancelledFuture<>();

    ImmediateCancelledFuture() {
      cancel(false);
    }
  }