CalendarDeserializer - Invalid date/time

[brisco5]

We're sending a SOAP message back to our server which attempts to
deserialize it.
Problem is there are some elements in there with no values,
specifically dates.
It looks something like this:

<assignedDate xsi:type="xsd:dateTime" />
<createdDate
xsi:type="xsd:dateTime">2006-07-19T18:23:46.327Z</createdDate>

It breaks on the assignedDate element with
java.lang.NumberFormatException: Invalid date/time

Is there a way to handle these empty elements (other than changing how
our xml is generated)?

Thanks,
Mike