feat: Implement topics module (beta)

[kewynakshlley]

Summary by cubic

Adds a beta Topics module to the Java SDK to manage email segmentation topics: create, get, update, remove, and list (with pagination). Exposes the service via Resend.topics() with typed request/response models.

• New Features
  • Topics service with create, get, update, remove, list, and list(ListParams).
  • Resend.topics() method to access the service.
  • Models for Topic and Create/Update/List/Remove request/response types.
  • Unit tests covering successful flows.

[cubic-dev-ai]

2 issues found across 11 files

Prompt for AI agents (all 2 issues)

Understand the root cause of the following 2 issues and fix them.


<file name="src/main/java/com/resend/services/topics/Topics.java">

<violation number="1" location="src/main/java/com/resend/services/topics/Topics.java:4">
Rule violated: **Initialisms and Acronyms Naming Conventions**

The imported helper name uses the all-uppercase acronym `URL`, which breaks the Initialisms and Acronyms Naming Conventions rule requiring acronyms to be cased like ordinary words (e.g., `UrlHelper`). Please rename the helper to comply.</violation>
</file>

<file name="src/test/java/com/resend/services/topics/TopicsTest.java">

<violation number="1" location="src/test/java/com/resend/services/topics/TopicsTest.java:19">
The Topics service is fully mocked throughout this class, so every test only asserts stubbed Mockito behavior and never executes the real Topics implementation. These tests give a false sense of coverage and will never fail even if the actual service is broken. Please instantiate and exercise the real Topics service (mocking only its dependencies) so the tests validate production logic.</violation>
</file>

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