sqlOrRestToEngineModel<T extends EngineModel>  method 
    Null safety
For using EngineModel with Sync
Example
  @Rest(
    name: 'user',
    toGenerator: 'SyncGeneratorHelper.engineModelToSqlOrRest(%INSTANCE_PROPERTY%)',
    fromGenerator: 'SyncGeneratorHelper.sqlOrRestToEngineModel<User>(User.fromJson, %DATA_PROPERTY%)',
  )
  @Sqlite(
    columnType: Column.varchar,
    toGenerator: 'SyncGeneratorHelper.engineModelToSqlOrRest(%INSTANCE_PROPERTY%)',
    fromGenerator: 'SyncGeneratorHelper.sqlOrRestToEngineModel<User>(User.fromJson, %DATA_PROPERTY%)',
  )
  final User user;
Implementation
static T sqlOrRestToEngineModel<T extends EngineModel>(
        Function fromJson, String sqlOrRestValue) =>
    fromJson(jsonDecode(sqlOrRestValue));