public async Task MapObjects()
        {
            var dm = await _dbContext.LoadModelAsync(null, "a2test.[MapObjects.NoKey.Load]");

            var md = new MetadataTester(dm);

            md.HasAllProperties("TRoot", "Document,Categories");
            md.IsItemRefObject("TDocument", "Category", "TCategory", FieldType.Object);
            md.IsItemIsArrayLike("TRoot", "Categories");
            md.IsItemRefObject("TRoot", "Categories", "TCategory", FieldType.Map);
        }