mutual mode booking how to add participants

[dasbid]

I'm trying to book in mutual mode requiring all "interviewers" to be required and present
but in the booking result the participants array is empty, only one of the interviewers is getting a calendar event

widget.init({
...
mode :"mutual",
resources ['resource_id_1','resource_id_2'],
participants : ['resource_id_1@email.com','resource_id_2@email.com']

...