Copy of immutable traversables not supported

[Till Rohrmann]

Hi,

I noticed currently that chill's TraversableSerializer cannot copy immutable Scala Traversables. Kryo's Serializer class offers a default implementation for the copy method which simply returns the original object if it is immutable. However, Serializer checks only its field immutable to figure out whether the object to copy is immutable and does not call isImmutable(). Chill's TraversableSerializer, though, overrides this method to be true but it does not set the field immutable to true. Consequently, the inherited copy method will fail with an exception.

I wonder whether this behaviour is intended or not. If not, then we should maybe fix the problem. What do you think?