fix(policies): handle null policies list in listDynamicPolicies

When the API returns {"policies": null} instead of {"policies": []},
the SDK now correctly returns an empty list instead of throwing NPE.

Fixes getaxonflow/axonflow-enterprise#40

Author: saurabhjain1592

src/main/java/com/getaxonflow/sdk/AxonFlow.java

@@ -1228,7 +1228,11 @@ public List<DynamicPolicy> listDynamicPolicies(ListDynamicPoliciesOptions option
             try (Response response = httpClient.newCall(httpRequest).execute()) {
                 // Agent proxy (Issue #886) returns {"policies": [...]} wrapper
                 DynamicPoliciesResponse wrapper = parseResponse(response, DynamicPoliciesResponse.class);
-                return wrapper != null ? wrapper.getPolicies() : java.util.Collections.emptyList();
+                // Handle null wrapper or null policies list (Issue #40)
+                if (wrapper == null || wrapper.getPolicies() == null) {
+                    return java.util.Collections.emptyList();
+                }
+                return wrapper.getPolicies();
             }
         }, "listDynamicPolicies");
     }