The issue is with
<bpmn2:collaboration id="_9L5_YNoyEeChpcAZezKhPA">
<bpmn2:participant id="_9NGSMNoyEeChpcAZezKhPA" name="Internal" processRef=""/>
</bpmn2:collaboration>
jBPM5 does not support this node (runtime) so web designer does not either. Unfortunately parsing fails hard if it encounters an element that is not supported. I will fix this to be just a log message ( https://issues.jboss.org/browse/JBPM-3354 ).
Hope this helps.