Freeplane has the functionality to execute Groovy scripts when the application starts. It's known as "init scripts" → https://docs.freeplane.org/?search=init
This add-on extends the functionality with the ability to execute scripts when a mindmap is opened, i.e. individually for each mindmap.
To execute a script for a mindmap, in your root node add an attribute named "scriptOnMapOpen", then use Tools->Edit script... to enter the Groovy code.
Note: The attribute name must start with "scriptOnMapOpen" but can have any suffix
Works with Freeplane version 1.7.10 and above.