Can't register ClosureSerializer

[mmikhulya]

With change 1c5562d users are forced to register ClosureSerializer on their own.
The problem is that it is not possible since Closure.class is private.

[magro]

Is this still an issue?

[mmikhulya]

Yes.

Class Closure is still declared as private static class at Kryo.java

So it is not possible to register it as recommended in javadoc here ClosureSerializer.java

[magro]

Ok, this is a fairly obvious issue. In PR #415 I also moved Closure from Kryo to ClosureSerializer to make the connection more obvious.