fix: ObjectContext#toString

assira.core/src/main/java/net/ranides/assira/reflection/walker/ObjectWalker.java

@@ -286,6 +286,10 @@ public class ObjectWalker {
             return type().isSubclass(type) || actual().isSubclass(type);
         }
 
+        @Override
+        public String toString() {
+            return "{" + name() + "=" + value() + "}";
+        }
     }
 
     private class CObject<T> extends CAbstract<T> implements ObjectContext<T> {