public class SetDefaultLanguage
{
    private readonly RequestDelegate _next;

    public SetDefaultLanguage(RequestDelegate next)
    {
        _next = next;
    }
    
    public async Task Invoke(HttpContext context)
    {
        HttpContextHelper.Current.Items["language"] = "en";
        
        await _next(context);
        return;
    }
}


// add to services

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{        
    ...       
    app.UseMiddleware<SetDefaultLanguage>();
    ...
}