public class FooBinder : IModelBinder
{
    public async Task BindModelAsync(ModelBindingContext bindingContext)
    {
        if (bindingContext.ModelType != typeof(Foo))
        {
            bindingContext.Result = ModelBindingResult.Failed();
            return;
        }

        var readResult = await bindingContext.HttpContext.Request.BodyReader.ReadAsync();
        var content = Encoding.UTF8.GetString(readResult.Buffer);

        if (content == null)
        {
            bindingContext.Result = ModelBindingResult.Failed();
            return;
        }

        var jo = JObject.Parse(content);

        // Set all properties with a [JsonProperty] attribute attached
        Foo? output = jo.ToObject<Foo>();

        if (output == null)
        {
            bindingContext.Result = ModelBindingResult.Failed();
            return;
        }

        output.BarProp = (string)jo.SelectToken("some.nested.property.from.json")!;

        bindingContext.Result = ModelBindingResult.Success(output);
        return;
    }
}

public class FooBinder : IModelBinder
{
    public async Task BindModelAsync(ModelBindingContext bindingContext)
    {
        if (bindingContext.ModelType != typeof(Foo))
        {
            bindingContext.Result = ModelBindingResult.Failed();
            return;
        }

        var readResult = await bindingContext.HttpContext.Request.BodyReader.ReadAsync();
        var content = Encoding.UTF8.GetString(readResult.Buffer);

        if (content == null)
        {
            bindingContext.Result = ModelBindingResult.Failed();
            return;
        }

        var jo = JObject.Parse(content);

        // Set all properties with a [JsonProperty] attribute attached
        Foo? output = jo.ToObject<Foo>();

        if (output == null)
        {
            bindingContext.Result = ModelBindingResult.Failed();
            return;
        }

        output.BarProp = (string)jo.SelectToken("some.nested.property.from.json")!;

        bindingContext.Result = ModelBindingResult.Success(output);
        return;
    }
}

'CollectionBinder' does not implement interface member 'IModelBinder.BindModelAsync(ModelBindingContext)'. 'CollectionBinder.BindModelAsync(ModelBindingContext)' cannot implement 'IModelBinder.BindModelAsync(ModelBindingContext)' because it does not have the matching return type of 'Task'.

'CollectionBinder' does not implement interface member 'IModelBinder.BindModelAsync(ModelBindingContext)'. 'CollectionBinder.BindModelAsync(ModelBindingContext)' cannot implement 'IModelBinder.BindModelAsync(ModelBindingContext)' because it does not have the matching return type of 'Task'.