code: public synchronized SerializerRegistry registerDefault(Class<?> baseType, TypeSerializerFactory factory) {
      defaultFactories.put(baseType, factory);
      return this;
    }
docs: Registers the given factory as a default serializer factory for the given base type.
  
  @param baseType The base type for which to register the serializer.
  @param factory The serializer factory.
  @return The serializer registry.