Outlook.com all day events date mismatch

[yevhene]

I create event on 16.05.2018 (My timezone is +2 Kyiv, Ukraine) in outlook.com

And then I pull event from nylas API and it is on 15.05.2018:

{
  "id": "25d2ktgflve600le2lezkh1hw",
  ...
  "title": "allday",
  "when": {
    "date": "2018-05-15",
    "object": "date"
  }
}

[yevhene]

Allday events become two-day events:

{
  "id": "3wylck7g4s6p4mk5wcsy8i3qu",
  ...
  "title": "allday",
  "when": {
    "end_date": "2018-06-07",
    "object": "datespan",
    "start_date": "2018-06-06"
}