Sync from monorepo 4591cce86e9e

Author: FusionAuth Automation

src/main/java/io/fusionauth/domain/AGENTS.md

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+# AGENTS.md — src/main/java/io/fusionauth/domain
+
+Rules for domain model classes under `io.fusionauth.domain`. These are the classes shared with client libraries and must maintain Java 8 compatibility.
+
+## Java 8 Compatibility (critical)
+- All code in `io.fusionauth.domain.*` **must be Java 8 compatible**.
+- Do not use Java 9+ language features (e.g., pattern variables with `instanceof`, `var`, records, sealed classes).
+- The rest of the codebase targets Java 21 — this directory is the exception.
+- Build and verify client libraries before pushing a PR that touches domain objects.
+
+## Domain Object Standards
+
+### Copy Constructors (required)
+Every domain object must provide a copy constructor.
+
+### equals / hashCode
+Use the IntelliJ default generator (Java 7+ style) for `equals` and `hashCode`. Ensure all fields are included.
+
+### toString
+Must use:
+```java
+return com.inversoft.json.ToString.toString(this);
+```
+
+### Field Visibility
+Prefer `public` fields over private fields with getters/setters.
+
+## Immutability and Constraints
+When a field is intentionally immutable or constrained, add a short comment explaining **why** — not just that it is.
+
+## Copy Constructor Completeness
+Ensure every field is handled in:
+- Copy constructor
+- `equals`
+- `hashCode`
+
+Missing fields in any of these are a common source of subtle bugs.
+
+## Client Library Impact
+Changes to domain objects ripple into client libraries published via git subtrees. After modifying domain objects:
+- Reflect changes in `fusionauth-client-builder`.
+- Build and verify client libraries before merging.