From: Adam Walczak <me_at_adamwalczak.info>
Date: Wed, 2 Feb 2011 10:12:21 +0100

In class com.entity.Days you have to annotate the getWeek method with
@XmlTransistent or @XmlIDREF
or class com.entity.Week you have to annotate the getDays method with
@XmlTransistent or @XmlIDREF

If you wont do this you'll be getting this exception because without
it the system would start generating an infinite xml like:

<day><weak><days><day><weak><days><day>....

-- 
Adam Walczak
www.adamwalczak.info
+48 604 188 992