HyphenateRouteParameterTransformer.cs

using Microsoft.AspNetCore.Routing;
using System.Text.RegularExpressions;

public class HyphenateRouteParameterTransformer : IOutboundParameterTransformer
{
    public string TransformOutbound(object value)
    {
        if (value == null) 
        { 
            return null; 
        }
        return Regex.Replace(value.ToString(), "([a-z])([A-Z])", "$1-$2").ToLower();
    }
}