No chance to customize 'null' when Custom JsonConverterAttribute(Type) is specified


I would like the chance to customize the "null" value that gets written whenever my JsonConverter is specified. However, JsonConverter.WriteJson() is never called when a property value is null.
The problem seems to be related to Line 103 in:
  JsonConverter converter = (member != null) ? member.Converter : null;
  if (value == null)
My motivation for customizing "null" is to do the following:
public enum Animals{
   Cats = 0x01,
   Dogs = 0x02,
   Fish = 0x04
public class Person {
    public Animals? Pets{ get; set; }
The JSON output of Person without any Pets would "{ Pets: null }". However, I'd prefer the output to be "{ Pets: [] }" so that it can more easily be used with KnockoutJS' "checked:" binding. However, doing so requires special handling by my converter to process 'null.'
Specifically, KO has two distinct behaviors when "checked:" is bound to "null" and "[]". When a checkbox is bound to "checked: null", KO writes "true/false" in the viewModel. When a checkbox is bound to "checked: []", KO pushes checkbox value attributes onto an array.
I know this is a really specific edge case, but as a user of the JsonConverter's API, I was expecting to be able to handle null in my JsonConverter.
This person also had a similar experience when trying to process "null" in his JsonConverter:
Closed Apr 16, 2012 at 10:52 PM by JamesNK
JsonConverters work with the value type which unfortunately means customizing null isn't possible, and its too late to change now.