curl --request GET \
  --url http://localhost:3000/projects/{projectId}/segments/{segmentId}/usage \
  --header 'Authorization: Bearer <token>'

{
  "statusCode": 123,
  "message": "OK",
  "data": {
    "usage_count": 123,
    "used_in_flags": [
      {
        "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
        "name": "<string>",
        "environment": "<string>"
      }
    ]
  }
}