Spotify.NET/SpotifyAPI.Web/Models/RecommendationSeedGenres.cs

using System.Collections.Generic;
using Newtonsoft.Json;

namespace SpotifyAPI.Web.Models
{
  public class RecommendationSeedGenres : BasicModel
  {
    [JsonProperty("genres")]
    public List<string> Genres { get; set; }
  }
}