setRootNode property
        
        dynamic
        setRootNode
        
      
getter/setter pair
      Fires on a request for change of root node for the tree, before the
update is made. An event object is passed to the function, containing
additional properties newRootId, previousRootId, redraw and
trigger.
API Docs: https://api.highcharts.com/highcharts/series.treegraph.events.setRootNode
Implementation
dynamic setRootNode;