DumpThemesToJson.cs

foreach(var mode in item.Value.Modes)
{
  string directory = $@"c:\temp\themes\{item.Key}";
  Directory.CreateDirectory(directory);

  var theme = item.Value.GetTheme(mode, item.Value.DefaultColor);
  theme.ThemeName = $"{item.Key} {mode}";

  File.WriteAllText(
    Path.Combine(directory, $"{item.Key}-{mode}.json"),
    JsonConvert.SerializeObject(
      theme,
      Formatting.Indented,
      new JsonSerializerSettings
      {
        ContractResolver = new ThemeContractResolver()
      }));
}

public class ThemeContractResolver : DefaultContractResolver
{
  private static Type ColorType = typeof(Color);

  protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
  {
    IList<JsonProperty> props = base.CreateProperties(type, memberSerialization);
    return props.Where(p => p.Writable).ToList();
  }

  protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
  {
    JsonProperty property = base.CreateProperty(member, memberSerialization);

    if (ColorType.IsAssignableFrom(property.PropertyType))
    {
      property.ShouldSerialize = (instance) =>
      {
        // Serialize Color property as long as we're not the default value
        return property.ValueProvider.GetValue(instance) is Color color
          && color != Color.Transparent;
      };
    }

    return property;
  }
}

public class WritablePropertiesOnlyResolver : DefaultContractResolver
{
  private static Type ColorType = typeof(Color);

  protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
  {
    IList<JsonProperty> props = base.CreateProperties(type, memberSerialization);
    return props.Where(p => p.Writable).ToList();
  }
}