ConversionException exception using xstream to convert org.apache.xerces.jaxp.datatype.XMLGregorianCalendarImpl

Hi,

I am trying to parse an xml to the corresponding object. My xml contains some date fields which are pointing to the class "org.apache.xerces.jaxp.datatype.XMLGregorianCalendarImpl". While trying to convert this xml to the object , I got the following exception. I ahd include the xercesImpl.jar in the classpath. But still issue not solved . The exception is given below.

com.thoughtworks.xstream.converters.ConversionException: org.apache.xerces.jaxp.datatype.XMLGregorianCalendarImpl : org.apache.xerces.jaxp.datatype.XMLGregorianCalendarImpl : org.apache.xerces.jaxp.datatype.XMLGregorianCalendarImpl : org.apache.xerces.jaxp.datatype.XMLGregorianCalendarImpl
---- Debugging information ----
message : org.apache.xerces.jaxp.datatype.XMLGregorianCalendarImpl : org.apache.xerces.jaxp.datatype.XMLGregorianCalendarImpl
cause-exception : com.thoughtworks.xstream.mapper.CannotResolveClassException
cause-message : org.apache.xerces.jaxp.datatype.XMLGregorianCalendarImpl : org.apache.xerces.jaxp.datatype.XMLGregorianCalendarImpl
class : com.att.csi.wlclient.InquireFanProfileResponseInfo
required-type : com.att.csi.wlclient.InquireFanProfileResponseInfo$Profile
path : /com.att.csi.wlclient.InquireFanProfileResponseInfo/profile/contractExpirationDate
line number : 112
-------------------------------

My xml file contains :

<contractExpirationDate class="org.apache.xerces.jaxp.datatype.XMLGregorianCalendarImpl">
<orig_year>2013</orig_year>
<orig_month>4</orig_month>
<orig_day>24</orig_day>
<orig_hour>-2147483648</orig_hour>
<orig_minute>-2147483648</orig_minute>
<orig_second>-2147483648</orig_second>
<orig_timezone>0</orig_timezone>
<year>2013</year>
<month>4</month>
<day>24</day>
<timezone>0</timezone>
<hour>-2147483648</hour>
<minute>-2147483648</minute>
<second>-2147483648</second>
</contractExpirationDate>

Pls help me ..its a critical situation.. Why xstream fails to convert org.apache.xerces.jaxp.datatype.XMLGregorianCalendarImpl to javax.xml.datatype.XMLGregorianCalendar ??????

Thanks,
Ziyad