Send Email Invitations with Google Hangouts Button

I'm trying to use Hangouts button specified in the following url:

http://ift.tt/GYDjVV

However, my goal is to open a Hangouts with a preloaded list of users, but I didn't find nothing about it in the Google Hangouts Developer's page.

In previous versions, I could use a parameter called "invites". Is there any way to do this in the current version ?

Thanks in advance