message: SyncConfig should be default constructible
diff: @@ -183,6 +183,7 @@ struct SyncConfig {
  bool simulate_integration_error = false;
  + SyncConfig() = default;
  explicit SyncConfig(std::shared_ptr<SyncUser> user, bson::Bson partition);
  explicit SyncConfig(std::shared_ptr<SyncUser> user, std::string partition);
  explicit SyncConfig(std::shared_ptr<SyncUser> user, const char* partition);
  