code: public void setDefaultSerializer (Class<? extends Serializer> serializer) {
  		if (serializer == null) throw new IllegalArgumentException("serializer cannot be null.");
  		defaultSerializer = new ReflectionSerializerFactory(serializer);
  	}
docs: Sets the serializer to use when no {@link #addDefaultSerializer(Class, Class) default serializers} match an object's type.
  Default is {@link FieldSerializer}.
  @see #newDefaultSerializer(Class)