curl --request POST \
  --url https://prv.stake.biya.io/stake/buyback/participations \
  --header 'Content-Type: application/json' \
  --data '
{
  "round_id": "<string>",
  "user_address": "<string>",
  "booked_amount": "<string>"
}
'

{
  "participation": {
    "id": "<string>",
    "participation_id": "<string>",
    "round_id": "<string>",
    "user_address": "<string>",
    "booked_amount": "<string>",
    "actual_amount": "<string>",
    "claimed_revenue": "<string>",
    "status": 123,
    "submit_tx_hash": "<string>",
    "claim_tx_hash": "<string>",
    "created_at": "<string>",
    "updated_at": "<string>"
  }
}