ConfigureAppConfiguration is not taken into account

[IgorBuchelnikov]

I use an alternative path to the configuration files. I set that path using HostBuilder.ConfigureAppConfiguration method:

WebHost.CreateDefaultBuilder(args)
  .UseStartup<Startup>()
  .ConfigureAppConfiguration((hostingContext, config) =>
  {
    config.SetBasePath(AlternativeConfigFilesPath);
  });

This works fine for appsettings.json and other configurations files.
loggerFactory.AddLog4Net(); throws an exception: Could not find file 'dllPath/log4net.config'