Laravel Nova - whitecube / nova-flexible-content

How to use belongsTo inside FLEXIBLE fields ?

    Flexible::make('Exmaple', 'blocks')
        ->addLayout('Exmaple', 'block', [

                BelongsTo::make('User'),

        ])->button('Add block'),

I am getting error

Call to protected method Whitecube\NovaFlexibleContent\Layouts\Layout::relationLoaded() from scope Laravel\Nova\Fields\BelongsTo

via Chebli Mohamed