page http://freemind.sourceforge.net/wiki/index.php/Scripting#API says
The scripts can access FreeMind's scripting API--application programming interface. Above all, the scripts would typically make use of the methods of MindMapController. The mind map controller is available to scripts as 'c'.
I suggest that it say something more like
These are the variables made available to scripts and their types:
def MindMapController c // the controller
def MindMapNode node // the node the script is run on
def HashMap cookies sScriptCookies // A hashmap of key-value pairs (WHAT IS THIS ANYWAY?)
It is suggested the programmer uses the Freemind sourced code and an IDE to explore the types and what methods are available.
Do you use an IDE for groovy scripts? Which plugin??