Here is my test project: https://github.com/pavelzazulia/FxNet.Web.Def.Api.Diagnostic

Spent huge of time but do not understand why .Include(t => t.Nodes) does not return referenced entities:

public class TreeRepository : ITreeRepository
{
    private DataBaseContext dataBaseContext;

    public TreeRepository(DataBaseContext dataBaseContext)
    {
        this.dataBaseContext = dataBaseContext;
    }

    public async Task<ITree> GetTreeAsync(string name)
    {
        var tree = dataBaseContext.Tree.Include(t => t.Nodes).SingleOrDefault(t => t.Name == name);

        if (tree == null)
        {
            var t = await dataBaseContext.Tree.AddAsync(new TreeTable { Name = name });
            await dataBaseContext.SaveChangesAsync();

            tree = t.Entity;
        }

        return tree;
    }
}

.Include(t => t.Nodes) should return nodes entities if they exist