final void addInitialException(Set<Throwable> seen) {
    checkNotNull(seen);
    if (!isCancelled()) {
      /*
       * requireNonNull is safe because:
       *
       * - This is a TrustedFuture, so tryInternalFastPathGetFailure will in fact return the failure
       *   cause if this Future has failed.
       *
       * - And this future *has* failed: This method is called only from handleException (through

    V sourceResult = null;
    Throwable throwable = null;
    try {
      if (localInputFuture instanceof InternalFutureFailureAccess) {
        throwable =
            InternalFutures.tryInternalFastPathGetFailure(
                (InternalFutureFailureAccess) localInputFuture);
      }
      if (throwable == null) {
        sourceResult = getDone(localInputFuture);
      }
    } catch (ExecutionException e) {

      this.callback = callback;
    }

    @Override
    public void run() {
      if (future instanceof InternalFutureFailureAccess) {
        Throwable failure =
            InternalFutures.tryInternalFastPathGetFailure((InternalFutureFailureAccess) future);
        if (failure != null) {
          callback.onFailure(failure);
          return;
        }
      }
      final V value;
      try {

      this.callback = callback;
    }

    @Override
    public void run() {
      if (future instanceof InternalFutureFailureAccess) {
        Throwable failure =
            InternalFutures.tryInternalFastPathGetFailure((InternalFutureFailureAccess) future);
        if (failure != null) {
          callback.onFailure(failure);
          return;
        }
      }
      final V value;
      try {