Serialization Xstream: Releasing 0.2.15

Hello,

I would like to propose the release of serialization.xstream version 0.2.15. This version should mitigate an issue that leads to reports disappearing (Error: Unable to deserialize Report)

Let me me know your thoughts on it or, if you have any objections.

cc: @mksd @dkayiwa

No objections from me :+1: