curl --request GET \
  --url http://{host}:{port}/{contextPath}/identity/groups \
  --header 'Authorization: Basic <encoded-value>'

{
  "groups": [
    {
      "id": "group1Id",
      "name": "group1"
    }
  ],
  "groupUsers": [
    {
      "firstName": "firstName",
      "lastName": "lastName",
      "displayName": "firstName lastName",
      "id": "anotherUserId"
    }
  ]
}