private BidirectionalDictionary <string, object> GetMappings(object context) { JsonSerializerInternalBase internalSerializer = context as JsonSerializerInternalBase; if (internalSerializer == null) { JsonSerializerProxy proxy = context as JsonSerializerProxy; if (proxy != null) { internalSerializer = proxy.GetInternalSerializer(); } else { throw new JsonException("The DefaultReferenceResolver can only be used internally."); } } return(internalSerializer.DefaultReferenceMappings); }