curl --request POST \
  --url https://api.fint.app/api/v1/contact/:contactId/item \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '{
  "itemsToDelete": [
    123
  ],
  "itemsToAdd": [
    123
  ]
}'

{}