Use cloning to prevent side effects

Author: digitalsadhu

lib/serializer.js

@@ -63,10 +63,10 @@ module.exports = function serializer (type, data, relations, options, cb) {
   var afterSerialize = (typeof model.afterJsonApiSerialize === 'function') ?
     model.afterJsonApiSerialize : defaultAfterSerialize;
 
-  serializeOptions = _.defaults(options, {
+  serializeOptions = _.assign(options, {
     type: type,
     results: data,
-    relationships: relations
+    relationships: _.cloneDeep(relations)
   });
   beforeSerialize(serializeOptions, function (err, serializeOptions) {
     if (err) return cb(err);