ATOMIC_HELPER.putNext(this, next);
    }

    void unpark() {
      // This is racy with removeWaiter. The consequence of the race is that we may spuriously call
      // unpark even though the thread has already removed itself from the list. But even if we did
      // use a CAS, that race would still exist (it would just be ever so slightly smaller).
      Thread w = thread;
      if (w != null) {
        thread = null;

import java.util.logging.Level;
import java.util.logging.Logger;
import org.checkerframework.checker.nullness.qual.Nullable;

/** Emulation for AbstractFuture in GWT. */
@SuppressWarnings("nullness") // TODO(b/147136275): Remove once our checker understands & and |.
@ElementTypesAreNonnullByDefault
public abstract class AbstractFuture<V extends @Nullable Object> extends InternalFutureFailureAccess
    implements ListenableFuture<V> {