curl --request POST \
  --url https://api.artemis.cynopsis.co/api/customer/{customerId}/assignee \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --header 'X-Domain-ID: <x-domain-id>' \
  --data '
{
  "customerId": 123,
  "main": true,
  "userId": 123
}
'

{
  "createdAt": {
    "date": 123,
    "day": 123,
    "hours": 123,
    "minutes": 123,
    "month": 123,
    "nanos": 123,
    "seconds": 123,
    "time": 123,
    "timezoneOffset": 123,
    "year": 123
  },
  "createdBy": {
    "email": "<string>",
    "firstName": "<string>",
    "fullName": "<string>",
    "id": 123,
    "lastName": "<string>"
  },
  "id": 123,
  "main": true,
  "updatedAt": {
    "date": 123,
    "day": 123,
    "hours": 123,
    "minutes": 123,
    "month": 123,
    "nanos": 123,
    "seconds": 123,
    "time": 123,
    "timezoneOffset": 123,
    "year": 123
  },
  "updatedBy": {
    "email": "<string>",
    "firstName": "<string>",
    "fullName": "<string>",
    "id": 123,
    "lastName": "<string>"
  },
  "userId": 123
}