POST /v3/instruments — zero-coupon-bond-instrument

Create a zero-coupon bond instrument (no coupons; redemption at par).

Request:
{
  "data": {
    "type": "zero-coupon-bond-instrument",
    "attributes": {
      "ccyCode":            "string (required) — ISO 4217",
      "countryCode":        "string (required) — ISO 3166-1 alpha-2 issuer domicile",
      "maturityDate":       "string, ISO 8601 (optional) — bond maturity",
      "name":               "string (required) — display name",
      "securityIdentifier": "string (required) — external security identifier"
    }
  }
}

Response (201 Created):
{
  "data": {
    "id": "string",
    "type": "zero-coupon-bond-instrument",
    "attributes": { /* same as request */ }
  }
}