The incoming data and extraOptions in validateWithBackbone are

effectively read-only.

@@ -55,7 +55,7 @@ public class Require {
         });
     }
 
-    public Map<String, Object> validateWithBackbone(String moduleId, String preInitEval, Map<String, Object> data, Map<String, Object> extraOptions) throws Exception {
+    public Map<String, Object> validateWithBackbone(String moduleId, String preInitEval, Map<String, ? extends Object> data, Map<String, ? extends Object> extraOptions) throws Exception {
         Function modelClass = require(moduleId);
         Scriptable modelInstance = container.newObject(modelClass);
         container.eval(loader, preInitEval, modelInstance);