How to obtain data lists from external sources and use it in the Enumeration menu in BRMS 6 ?

Issue

• The goal is to obtain data lists (like Person.age) from external sources (like return values from an external class's method call com.yourco.DataHelper.getListOfAges()) and use it in an Enumeration menu while developing a rule in Guided Rule Editor of Business Central. What are the steps required to achieve it in BRMS 6 ?