In milestones, the designer can define triggering expressions using DRL pattern matching language.
E.g. org.kie.api.runtime.process.CaseData(data.get("ok") == true)
Writing and reading such expressions is quite difficult.
A great improvement is having the package imported by default, so the expression can become this:
CaseData(data.get("ok") == true)
Or even better (using OOPath):
CaseData( data["ok"] == true)