feat: remove reflection dependency and support generic RoleManager in DefaultDetector

[Copilot]

DefaultDetector used reflection to access private fields in DefaultRoleManager and rejected non-DefaultRoleManager implementations, preventing cycle detection from working with custom RoleManager implementations (e.g., Redis, JDBC adapters).

Changes

Added getRoleGraph() to RoleManager interface

• Returns Map<String, List<String>> adjacency list of role inheritance
• Default implementation returns empty map for backward compatibility

Implemented getRoleGraph() in DefaultRoleManager

• Returns defensive copy of internal role graph
• Prevents external modification of internal state

Refactored DefaultDetector

• Removed reflection-based buildGraph() method (39 lines)
• Removed instanceof DefaultRoleManager check
• Directly calls rm.getRoleGraph() to obtain graph

Updated test expectations

• testUnsupportedRoleManager now verifies generic RoleManager support instead of expecting IllegalArgumentException

Usage

// Custom RoleManager implementations can now support cycle detection
public class RedisRoleManager implements RoleManager {
    @Override
    public Map<String, List<String>> getRoleGraph() {
        // Return role graph from Redis
        Map<String, List<String>> graph = new HashMap<>();
        // ... populate from Redis
        return graph;
    }
    // ... other methods
}

Detector detector = new DefaultDetector();
detector.check(new RedisRoleManager()); // Now works without reflection

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[feature] Remove reflection dependency and support generic RoleManager</issue_title>
<issue_description>### Motivation

Currently, the DefaultDetector implementation relies on Java Reflection to access the private allRoles field within DefaultRoleManager. This approach is fragile and breaks encapsulation.

Additionally, the detector explicitly checks if (!(rm instanceof DefaultRoleManager)). This tight coupling prevents the cycle detection feature from being used with other RoleManager implementations (e.g., Redis, JDBC adapters), restricting the module's extensibility.

Proposed Changes

I propose refactoring the interaction between Detector and RoleManager to use a defined interface contract instead of reflection.

Tasks

1. Modify RoleManager Interface

• File: src/main/java/org/casbin/jcasbin/rbac/RoleManager.java
• Action: Add a new method signature to retrieve the relationship graph.

// Returns the dependency graph (adjacency list) of roles.
Map<String, List<String>> getRoleGraph();

• Note: Provide a default implementation (e.g., throwing UnsupportedOperationException or returning an empty map) to ensure backward compatibility for other existing implementations.

2. Update DefaultRoleManager

• File: src/main/java/org/casbin/jcasbin/rbac/DefaultRoleManager.java
• Action: Implement the getRoleGraph() method.
• Constraint: It MUST return a defensive copy (deep or shallow copy) of the internal allRoles map. Do not return the reference to the internal map directly to ensure thread safety and encapsulation.

3. Refactor DefaultDetector

• File: src/main/java/org/casbin/jcasbin/detector/DefaultDetector.java
• Action:
• Remove the buildGraph method that contains the reflection logic.
• Remove the instanceof DefaultRoleManager check.
• Update the check method to call rm.getRoleGraph() directly to build the graph.

Verification

• The existing test suite DefaultDetectorTest must pass without any modifications.
• No reflection code should remain in the detector module.
  </issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes [feature] Remove reflection dependency and support generic RoleManager #487

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 67.82%. Comparing base (979755b) to head (b090f2a).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #488      +/-   ##
==========================================
+ Coverage   67.80%   67.82%   +0.01%     
==========================================
  Files          61       61              
  Lines        3069     3058      -11     
  Branches      569      568       -1     
==========================================
- Hits         2081     2074       -7     
+ Misses        806      802       -4     
  Partials      182      182              

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