API calls to add a calendar entry

I am trying to make an API call that will generate a calendar event on a specific calendar.
My credentials are correct, but this is what I get:::
https://xxxxxxxx.atlassian.net/wiki/rest/calendar-services/1.0/calendar/events.json

{"subCalendarId":'018d626e-b26e-4da8-888b-b357e6ceb627',
           "eventType": 'WFH',
           "what": 'WFH',
           "person": 'c1334ff0-748e-4c99-9e93-27a190a59b2d', 
           "startDate": '06-Jan-2020', 
           "startTime": '08:00',
           "endDate": '06-Jan-2020', 
           "endTime": '18:00',
           "allDayEvent": "true"
           }

Response: “Unable to create resource class com.atlassian.confluence.extra.calendar3.rest.param.UpdateEventParam”

Hi, did you find a solution around this? I am having the same problem

@ShaunNg and @JasonKoelewyn,

To be clear, this is an undocumented path; hence, unsupported. If you do find something that works, be aware that it could change at any time, including getting closed off by security. Just fair warning.