Using Extension in ASP.NET application - .NET 6

I'm trying to get NEST working in an ASP.NET application. I'm following the guide https://blexin.com/en/blog-en/how-to-integrate-elasticsearch-in-asp-net-core/#highlighter_541789. I'm trying to figure out how to call AddElasticsearch correctly on the builder. I've tried a few ways but keep getting compiler complaints.

Extensions.cs

public static class Extensions
{
    public static void AddElasticsearch(this IServiceCollection services, IConfiguration configuration)
    {
        var url = configuration["elasticsearch:url"];
        var defaultIndex = configuration["elasticsearch:index"];

        var settings = new ConnectionSettings(new Uri(url)).DefaultIndex(defaultIndex);

        AddDefaultMappings(settings);

        var client = new ElasticClient(settings);

        services.AddSingleton(client);

        CreateIndex<LegiscanModelBill>(client, defaultIndex);
    }

    private static void AddDefaultMappings(ConnectionSettings settings) => settings.DefaultMappingFor<LegiscanModelBill>(m => m);

    // private static void CreateIndex<T>(IElasticClient client, string indexName)
    // {
    //     var createIndexResponse = client.Indices.Create(indexName,
    //         index => index.Map<LegiscanModelBill>(x => x.AutoMap())
    //     );
    // }

    private static void CreateIndex<T>(ElasticClient client, string indexName) where T : class
    {
        client.Indices.Create($"{indexName}_{typeof(T).ToString}", i => i.Map<T>(m => m.AutoMap()));
    }
}

Program.cs

var builder = WebApplication.CreateBuilder(args);

builder.Services
    .AddElasticsearch(options => options.configuration)
    .AddGraphQLServer()
    .AddQueryType<Query>();


var app = builder.Build();

app.MapGraphQL();

app.Run();

compiler error

Cannot convert lambda expression to type 'IConfiguration' because it is not a delegate type