Add JsonVariant::link() (resolves #1343)

src/ArduinoJson/Object/MemberProxy.hpp

@@ -135,6 +135,10 @@ class MemberProxy : public VariantOperators<MemberProxy<TObject, TStringRef> >,
     getUpstreamMember().remove(key);
   }
 
+  FORCE_INLINE void link(VariantConstRef value) {
+    getOrAddUpstreamMember().link(value);
+  }
+
   template <typename TValue>
   FORCE_INLINE typename VariantTo<TValue>::type to() {
     return getOrAddUpstreamMember().template to<TValue>();

src/ArduinoJson/Object/ObjectRef.hpp

@@ -278,7 +278,7 @@ struct Converter<ObjectConstRef> {
 
   static bool checkJson(VariantConstRef src) {
     const VariantData* data = getData(src);
-    return data && data->isObject();
+    return data && data->resolve()->isObject();
   }
 };