Field naming inconsistency: last_4 in webhooks vs last4 in API responses

[shahzaibm10c]

Field naming inconsistency: last_4 in webhooks vs last4 in API responses

Environment

• Checkout SDK version: N/A (API inconsistency)
• Platform and version: PHP 8.x
• Operating System and version: All platforms

Description

Checkout.com uses inconsistent field names for card's last four digits:

• Webhook events use last_4 (with underscore)
• REST API responses use last4 (no underscore)

Expected behavior

Field name should be consistent across all endpoints - either last4 or last_4 everywhere.

Current behavior

Webhook event (card_verified):

"source" => [
  "last_4" => "0018"  // With underscore
]

API response (GET /payments/{id}):

"source" => [
  "last4" => "0018"  // No underscore
]

Steps to reproduce

1. Receive a card_verified webhook - observe last_4 field
2. Call GET /payments/{id} - observe last4 field
3. Note the inconsistency

Possible solution

Standarize on one naming convention (preferably last_4 with underscore) across all endpoints. Provide deprecation period for the old field name.

Current workaround required:

$lastFour = $data['last_4'] ?? $data['last4'] ?? null;

Additional information

This affects all integrations using both webhooks and REST API. All other card fields (expiry_month, fingerprint, etc.) are consistent - only last4/last_4 has this issue.