A custom deserializer for dictionaries.

PropertyBagDeserializer.cs

public class PropertyBagDeserializer : JsonConverter
{
  public override bool CanRead => true;

  public override bool CanWrite => false;

  public override bool CanConvert(Type objectType)
  {
    return true;
  }
  
  public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
  {
    return ReadValue(reader, serializer);
  }
  
  private static object ReadValue(JsonReader reader, JsonSerializer serializer)
  {
    if (reader.TokenType == JsonToken.StartObject)
    {
      return ReadObjectValue(reader, serializer);
    }
    else if (reader.TokenType == JsonToken.StartArray)
    {
      return ReadArrayValue(reader, serializer);
    }
    else
    {
      return ReadSimpleValue(reader, serializer);
    }
  }
  
  private static object ReadObjectValue(JsonReader reader, JsonSerializer serializer)
  {
    reader.Read();
    var dictionary = new Dictionary<string, object>();
    while (reader.TokenType != JsonToken.EndObject)
    {
      if (reader.TokenType == JsonToken.PropertyName)
      {
        var propertyName = (string) reader.Value;
        reader.Read();
        dictionary[propertyName] = ReadValue(reader, serializer);
      }
    }
    reader.Read();
    return dictionary;
  }

  private static object ReadArrayValue(JsonReader reader, JsonSerializer serializer)
  {
    reader.Read();
    var list = new List<object>();
    while (reader.TokenType != JsonToken.EndArray)
    {
      list.Add(ReadValue(reader, serializer));
    }
    reader.Read();
    return list;
  }

  private static object ReadSimpleValue(JsonReader reader, JsonSerializer serializer)
  {
    var val = serializer.Deserialize(reader);
    reader.Read();
    return val;
  }
  
  public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
  {
    throw new NotImplementedException();
  }
}