private void pushDeltaFromRoot(@Nullable IntervalNode<T> node) {
    if (node != null) {
      long packedOffsets = node.cachedDeltaUpToRoot;
      if (IntervalNode.allDeltasUpAreNull(packedOffsets) && node.isValid() && IntervalNode.modCount(packedOffsets) == getModCount()) return;
      pushDeltaFromRoot(node.getParent());
      pushDelta(node);
    }
  }
private void pushDeltaFromRoot(@Nullable IntervalNode<T> node)