lower-case-contract-resolver.cs

public class LowerCaseResolver<T> : DefaultContractResolver
{
    protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
    {
        JsonProperty property = base.CreateProperty(member, memberSerialization);
        if (property.DeclaringType == typeof(T))
        {
            property.PropertyName = property.PropertyName.ToLower();
        }

        return property;
    }

}