message: Only handle empty payloads for update requests (lib)
diff: @@ -6441,7 +6441,10 @@ void Context::syncCollectJSON(Json::Value &array, const std::vector<T*> &source)
  // When removing this, see the SyncPayload method, it relies on returning GUIDs
  syncTranslateGUIDToLocalID(payload);
  - if (!payload.isNull()) {
  + // If updating, there always has to be a payload
  + // When creating, it hypothetically doesn't need to be there
  + // Deleting doesn't have any payload at all
  + if (!payload.isNull() || i->SyncType() != "update") {
  item["payload"] = payload;
  item["type"] = i->SyncType();
  item["meta"] = i->SyncMetadata();
  