curl --request POST \
  --url https://api2.rhombussystems.com/api/accesscontrol/addUsersToAccessControlGroup \
  --header 'Content-Type: application/json' \
  --header 'x-auth-apikey: <api-key>' \
  --header 'x-auth-scheme: <x-auth-scheme>' \
  --data '
{
  "groupUuid": "AAAAAAAAAAAAAAAAAAAAAA",
  "userUuids": [
    "AAAAAAAAAAAAAAAAAAAAAA"
  ]
}
'

{
  "groupMembers": [
    {
      "createdAtMillis": 123,
      "groupUuid": "AAAAAAAAAAAAAAAAAAAAAA",
      "orgUuid": "AAAAAAAAAAAAAAAAAAAAAA",
      "type": "RHOMBUS_ACCESS_CONTROL",
      "updatedAtMillis": 123,
      "userUuid": "AAAAAAAAAAAAAAAAAAAAAA"
    }
  ]
}