public class RateLimitConfiguration : IRateLimitConfiguration
{
        
    protected virtual void RegisterResolvers()
    {
        if (!string.IsNullOrEmpty(ClientRateLimitOptions?.ClientIdHeader))
        {
            ClientResolvers.Add(new ClientHeaderResolveContributor(HttpContextAccessor, ClientRateLimitOptions.ClientIdHeader));
        }
        // the contributors are resolved in the order of their collection index
        if (!string.IsNullOrEmpty(IpRateLimitOptions?.RealIpHeader))
        {
                IpResolvers.Add(new IpHeaderResolveContributor(HttpContextAccessor, IpRateLimitOptions.RealIpHeader));
        }
        IpResolvers.Add(new IpConnectionResolveContributor(HttpContextAccessor));
    }
}

public class CustomRateLimitConfiguration : RateLimitConfiguration
{
    protected override void RegisterResolvers()
    {
    	base.RegisterResolvers();
    	ClientResolvers.Add(new ClientQueryStringResolveContributor(HttpContextAccessor, "queryStringParamName"));
    }
}

services.AddSingleton<IRateLimitConfiguration, CustomRateLimitConfiguration>();