Comments are not removed on optimization

[rahul7720]

configuration:

            services.AddWebOptimizer(pipeline =>
            {
                pipeline.MinifyCssFiles();;
                pipeline.MinifyJsFiles();;
                pipeline.AddCssBundle("/css/style.css", "**/*.css");
                pipeline.AddJavaScriptBundle("/js/script.js", "**/*.js");
            });

And I can see the code comments on the files are still exist:

/*!
 * Bootstrap Grid v4.3.1 (https://getbootstrap.com/)
 * Copyright 2011-2019 The Bootstrap Authors
 * Copyright 2011-2019 Twitter, Inc.
 * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
 */

Is there any way to remove the comments on optimization?