1.1.1

🚀 UPC 1.1.1

Corrective release making submerchantExternalId optional across the payment-creation and refund
paths, and adding an optional currency to refunds — non-EUR configurations can now be paid and
refunded, which 1.1.0 made impossible.

🐛 Fixed

• 🏬 submerchantExternalId is no longer required — it belongs to the UDV/MID configuration for
  the payment's currency, not to a payment method: the EUR configurations own a submerchant,
  the ones used for other currencies own none. 1.1.0 required it everywhere, so a non-EUR payment
  or refund was rejected with 400 "Invalid parameter." and had no way through.
  CommonFieldsDto::__construct()'s 5th parameter is now ?string = null, and
  UnifiedApiPaymentService::createRefund()'s 5th is too — both still in place, so existing
  5-argument positional callers are unaffected.
• 🕳️ An empty submerchant is treated as "none" — BuildsCommonPayloadBody and createRefund()
  omit the key entirely when it is null or '', since a CMS reading an unset value out of
  its own settings storage yields '' far more often than a real null, and '' is rejected by
  the API just like a submerchant the configuration does not own. When present, the key keeps its
  original position in the body.

✨ Added

• 💱 currency on refunds — UnifiedApiPaymentService::createRefund() takes an optional
  trailing ?string $currency = null, sent only when non-null and non-empty. Until now no currency
  was sent at all, so $amount's minor units travelled bare for the platform to interpret —
  unambiguous only while every payment used the account's default currency, and a real gap for a
  multi-currency merchant.

♻️ Changed

• createRefund() no longer rejects an empty submerchantExternalId locally with
  InvalidRefundRequestException — orderId and description keep that fail-fast guard.
• BuildsCommonPayloadBody::buildRedirectBody() extracted from buildPayloadBody(); no behavior
  change.
• Design rationale in CLAUDE.md and .env.example corrected in place rather than deleted,
  including the caveat that the staging run which confirmed the fix changed both
  submerchantExternalId and currency at once.

✅ Quality

PHPStan level 8, PHP-CS-Fixer, PHPUnit, and CI verifying PHP 7.1–8.2 compatibility — all clean on
this release branch. Seven unit tests added or reworked around the new omission rules, plus the
refund integration test reworked to run on a configuration that owns no submerchant.

📋 Requirements

• PHP ≥7.4 to install/develop (build-tooling floor only — shipped source runs on PHP 7.1)
• Runtime dependency: giggsey/libphonenumber-for-php

🔗 Full Changelog: 1.1.0...1.2.0