[ACL-290] Add sub_merchants support to Payments module

[federico1525]

Summary

• Implements sub_merchants functionality for payments module to achieve feature parity with payouts
• Adds SubMerchants, UltimateCounterparty, BusinessClient, and BusinessDivision classes matching OpenAPI specification
• Updates CreatePaymentRequest and PaymentDetail to include subMerchants field

Test plan

• Build passes without compilation errors
• All existing tests continue to pass
• New unit tests verify SubMerchants functionality
• CreatePaymentRequest accepts subMerchants parameter
• PaymentDetail includes subMerchants in responses

🤖 Generated with Claude Code

[Copilot]

Pull Request Overview

This PR implements support for sub‐merchants in the payments module by adding new classes (BusinessClient, BusinessDivision, UltimateCounterparty, and SubMerchants) and updating relevant request and response entities.

• Introduces sub_merchants functionality through new domain entities and associated builders.
• Adds tests verifying the creation and usage of sub‐merchants in both requests and responses.
• Updates PaymentDetail and CreatePaymentRequest to include subMerchants fields.

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
SubMerchantsTest.java	Adds tests for creating BusinessClient, BusinessDivision, and SubMerchants.
CreatePaymentRequestSubMerchantsTest.java	Verifies that CreatePaymentRequest accepts and processes subMerchants correctly.
UltimateCounterparty.java	Provides the abstract base and builder methods for sub‐merchant counterparties.
SubMerchants.java	Defines the container class for an UltimateCounterparty instance.
BusinessDivision.java	Implements BusinessDivision with its required fields.
BusinessClient.java	Implements BusinessClient with its required fields.
PaymentDetail.java	Updates PaymentDetail to include the subMerchants field.
CreatePaymentRequest.java	Updates CreatePaymentRequest to include the subMerchants field with appropriate documentation.

Comments suppressed due to low confidence (1)

src/main/java/com/truelayer/java/payments/entities/paymentdetail/PaymentDetail.java:41

• [nitpick] Consider adding a Javadoc comment for the 'subMerchants' field to maintain consistency with similar fields in other classes (e.g., in CreatePaymentRequest) and to provide clarity on its intended use.

private SubMerchants subMerchants;

[dili91]

I think we should amend the version of the library included in the gradle.properties file.
If this is a non-breaking change, a minor version bump should be fine

[federico1525]

Thanks for the feedback! I've addressed both comments:

1. ✅ Added Javadoc comment for the subMerchants field in PaymentDetail.java for consistency with other fields
2. ✅ Bumped library version from 17.2.0 to 17.3.0 in gradle.properties (minor version bump for this new feature)

Changes are ready for review.

[federico1525]

Re: acceptance tests for subMerchants field - Good question! I'm not sure about the acceptance test requirements for this new field. @tl-Roberto-Mancinelli could you provide feedback on whether we need acceptance tests for the subMerchants field?

[federico1525]

✅ Update: I've now added a parametrized acceptance test for the subMerchants field that tests both BusinessClient and BusinessDivision counterparty types. The test verifies that sub-merchants data is properly preserved during payment creation and retrieval.

[dili91]

🥳