Get transaction by external ID

[
  {
    "agreement_payment_type": "recurring",
    "amount": 1000,
    "authorisation_mode": "web",
    "authorisation_summary": {
      "three_d_secure": {
        "required": true,
        "version": "2.1.0"
      }
    },
    "card_details": {
      "billing_address": {
        "city": "London",
        "country": "GB",
        "county": "county",
        "line1": "address line 1",
        "line2": "address line 2",
        "postcode": "Ex 8RR"
      },
      "card_brand": "Visa",
      "card_type": "credit",
      "cardholder_name": "J Doe",
      "expiry_date": "11/43",
      "first_digits_card_number": "424242",
      "last_digits_card_number": "4242"
    },
    "credential_external_id": "7a7a718cb8b0401f8b8f4cdda9804073",
    "description": "New passport application",
    "email": "citizen@example.org",
    "exemption": {
      "outcome": {
        "result": "honoured"
      },
      "requested": true,
      "type": "corporate"
    },
    "fee": 2,
    "gateway_account_id": "1",
    "gateway_payout_id": "po_mdoiu23jkdj1kj23sd",
    "gateway_transaction_id": "fd21-1mdknkls1-2121-csdf",
    "language": "en",
    "net_amount": -2,
    "parent_transaction_id": "4dfdhapsdgftgkpp029d5kdfau5f",
    "payment_provider": "sandbox",
    "reason": "fraudulent",
    "reference": "payment reference",
    "refund_summary": {
      "status": "unavailable"
    },
    "refunded_by": "dj8923eihsdih23hkjfe8d",
    "refunded_by_user_email": "test@example.org",
    "return_url": "https://service-name.gov.uk/transactions/12345",
    "service_id": "baea0585e30d4acbb438524fca82b51e",
    "settlement_summary": {
      "settled_date": "2022-01-26"
    },
    "source": "CARD_API",
    "state": {
      "can_retry": true,
      "code": "P0030",
      "finished": true,
      "message": "Payment was cancelled by the user",
      "status": "cancelled"
    },
    "total_amount": 1000,
    "transaction_id": "9np5pocnotgkpp029d5kdfau5f",
    "transaction_type": "PAYMENT",
    "wallet_type": "APPLE_PAY"
  }
]