title: How to get groups and contact ids of WhatsApp using API?
body: <p>I'm developing an Android app that creates a whitelist of over 400 contacts and groups of WhatsApp to send them a scheduled message. I found an API to send a message using WhatsApp by passing the message and the receipt contact (person or group), but I didn't find another API to get all group ids of WhatsApp.</p>
  <p>How to retrieve all WhatsApp groups' ids, using Android Java?</p>