Best practice to limit the capability of Groovy classes

Hi team,
Syncope is offering the possibility to extend / customize the base behavior on every deployment by allowing to provide custom implementations of a few Java interfaces; such implementations can be provided either as Java or Groovy classes [1], with the latter being particularly attractive as the machinery is set for runtime reload.

I was wondering if there is any best-practice available to limit what could be done by Groovy classes (e.g. System.exit, spawning new processes, etc.).
I found [2] and a few other references which looks anyway either old or not for general purpose.

Can you suggest something else?

TIA
Regards.

[1] https://syncope.apache.org/docs/4.0/reference-guide.html#implementations
[2] https://levelup.gitconnected.com/secure-groovy-script-execution-in-a-sandbox-ea39f80ee87

-- 
Francesco Chicchiriccò

Tirasa - Open Source Excellence
http://www.tirasa.net/

Member at The Apache Software Foundation
Syncope, Cocoon, Olingo, CXF, OpenJPA
https://about.me/ilgrosso