curl --request POST \
  --url 'https://api.stateset.com/api/v1/negotiations/{id}/reject' \
  --header 'Authorization: Bearer YOUR_API_KEY'

{
  "buyer_agent_id": "string",
  "created_at": "string",
  "currency": "string",
  "current_offer": "string",
  "id": "string",
  "max_rounds": 1,
  "offer_count": 1,
  "rounds": 1,
  "seller_agent_id": "string",
  "status": "string"
}