The proper API response to send would look like this:

{
"countries": [
    {
        "attendeeCount": 1,
        "attendees": [
            "cbrenna@hubspotpartners.com"
        ],
        "name": "Ireland",
        "startDate": "2017-04-29"
    },
    {
        "attendeeCount": 0,
        "attendees": [],
        "name": "United States",
        "startDate": null
    },
    {
        "attendeeCount": 3,
        "attendees": [
            "omajica@hubspotpartners.com",
            "taffelt@hubspotpartners.com",
            "tmozie@hubspotpartners.com"
        ],
        "name": "Spain",
        "startDate": "2017-04-28"
    }
]
}