Following example but API not working

Following example but API not working

Hello, I have follow the exact example in the documentation. But i cannot get the API worked. I have no idea what to put inside this line:
addmap.put("updateData","{'':'1'}");

API: api/leave/updateInitialBalance

Example scenario-Increase leave balance by 1 day, if the over time is more than 2 hours a day
https://www.zoho.com/people/help/adminguide/automation-customfunctions.html


Moreover, how could i get the full API reference for every module in Zoho People. Thanks.