shouldRelayout method
Override this method to return true when the children need to be laid out.
This should compare the fields of the current delegate and the given
oldDelegate and return true if the fields are such that the layout would
be different.
Implementation
@override
bool shouldRelayout(NodeFlowLayoutDelegate<T> oldDelegate) {
// Always relayout to handle position changes
// The Observer in _buildNodesLayer will handle tracking position changes
return true;
}