Remove reflection dependency and support generic RoleManager

- Added getRoleGraph() method to RoleManager interface with default implementation
- Implemented getRoleGraph() in DefaultRoleManager with defensive copy
- Removed reflection-based buildGraph() method from DefaultDetector
- Removed instanceof check to support any RoleManager implementation
- Updated test to reflect new behavior (now accepts any RoleManager)

Co-authored-by: hsluoyz <3787410+hsluoyz@users.noreply.github.com>

Author: Copilot

src/main/java/org/casbin/jcasbin/detector/DefaultDetector.java

@@ -14,7 +14,6 @@
 
 package org.casbin.jcasbin.detector;
 
-import org.casbin.jcasbin.rbac.DefaultRoleManager;
 import org.casbin.jcasbin.rbac.RoleManager;
 
 import java.util.*;
@@ -32,15 +31,8 @@ public class DefaultDetector implements Detector {
      */
     @Override
     public String check(RoleManager rm) {
-        if (!(rm instanceof DefaultRoleManager)) {
-            throw new IllegalArgumentException("DefaultDetector only supports DefaultRoleManager");
-        }
-        
-        DefaultRoleManager drm = (DefaultRoleManager) rm;
-        
         // Build adjacency list from the role manager
-        // Using local data structures to avoid sharing references with RoleManager's internal state
-        Map<String, List<String>> graph = buildGraph(drm);
+        Map<String, List<String>> graph = rm.getRoleGraph();
 
         // Perform DFS to detect cycles
         Set<String> visited = new HashSet<>();
@@ -59,35 +51,6 @@ public String check(RoleManager rm) {
         return null;
     }
 
-    /**
-     * Builds a directed graph (adjacency list) from the DefaultRoleManager.
-     * Each role points to the roles it inherits (its parent roles).
-     */
-    private Map<String, List<String>> buildGraph(DefaultRoleManager drm) {
-        Map<String, List<String>> graph = new HashMap<>();
-        
-        try {
-            // Use reflection to access the package-private allRoles field
-            java.lang.reflect.Field allRolesField = DefaultRoleManager.class.getDeclaredField("allRoles");
-            allRolesField.setAccessible(true);
-            @SuppressWarnings("unchecked")
-            Map<String, ?> allRoles = (Map<String, ?>) allRolesField.get(drm);
-            
-            // Iterate through all roles and get their parent roles
-            for (String roleName : allRoles.keySet()) {
-                List<String> parentRoles = drm.getRoles(roleName);
-                graph.put(roleName, new ArrayList<>(parentRoles));
-            }
-        } catch (NoSuchFieldException e) {
-            throw new RuntimeException("Failed to access 'allRoles' field in DefaultRoleManager via reflection. " +
-                    "The field may have been renamed or removed.", e);
-        } catch (IllegalAccessException e) {
-            throw new RuntimeException("Failed to access 'allRoles' field in DefaultRoleManager via reflection. " +
-                    "Permission denied to access the field.", e);
-        }
-        
-        return graph;
-    }
 
     /**
      * Performs depth-first search to detect cycles in the graph using an iterative approach.

src/main/java/org/casbin/jcasbin/rbac/DefaultRoleManager.java

@@ -268,4 +268,21 @@ public String toString() {
     public void printRoles() {
         Util.logPrintfInfo("{}", this);
     }
+
+    /**
+     * getRoleGraph returns the dependency graph (adjacency list) of roles.
+     * Each key represents a role name, and the corresponding value is a list of role names
+     * that the key role inherits from (parent roles).
+     * 
+     * @return a defensive copy of the role inheritance graph
+     */
+    @Override
+    public Map<String, List<String>> getRoleGraph() {
+        Map<String, List<String>> graph = new HashMap<>();
+        for (String roleName : allRoles.keySet()) {
+            List<String> parentRoles = getRoles(roleName);
+            graph.put(roleName, new ArrayList<>(parentRoles));
+        }
+        return graph;
+    }
 }

src/main/java/org/casbin/jcasbin/rbac/RoleManager.java

@@ -14,7 +14,9 @@
 
 package org.casbin.jcasbin.rbac;
 
+import java.util.Collections;
 import java.util.List;
+import java.util.Map;
 
 public interface RoleManager {
     /**
@@ -75,4 +77,15 @@ public interface RoleManager {
      * printRoles prints all the roles to log.
      */
     void printRoles();
+
+    /**
+     * getRoleGraph returns the dependency graph (adjacency list) of roles.
+     * Each key represents a role name, and the corresponding value is a list of role names
+     * that the key role inherits from (parent roles).
+     * 
+     * @return a map representing the role inheritance graph, or an empty map if not supported.
+     */
+    default Map<String, List<String>> getRoleGraph() {
+        return Collections.emptyMap();
+    }
 }

src/test/java/org/casbin/jcasbin/main/DefaultDetectorTest.java

@@ -214,9 +214,10 @@ public void testLargeGraphWithCycle() {
         assertTrue("Result should contain 'Cycle detected'", result.contains("Cycle detected:"));
     }
 
-    @Test(expected = IllegalArgumentException.class)
+    @Test
     public void testUnsupportedRoleManager() {
-        // Test with a RoleManager that is not DefaultRoleManager
+        // Test with a RoleManager that uses the default getRoleGraph() implementation
+        // The default implementation returns an empty map, so no cycles should be detected
         RoleManager rm = new RoleManager() {
             @Override
             public void clear() {}
@@ -247,7 +248,8 @@ public void printRoles() {}
         };
 
         Detector detector = new DefaultDetector();
-        detector.check(rm); // Should throw IllegalArgumentException
+        String result = detector.check(rm);
+        assertNull("Expected no cycle with default getRoleGraph() implementation", result);
     }
 
     @Test