[JBPM-10203] Fixing null pointer exception for cancelActivity (#2342) (…

…#2344)

* [JBPM-10203] Fixing null pointer exception for cancelActivity

* Update jbpm-bpmn2/src/main/java/org/jbpm/bpmn2/xml/BoundaryEventHandler.java



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Co-authored-by: Francisco Javier Tirado Sarti <65240126+fjtirado@users.noreply.github.com>
Co-authored-by: Gonzalo Muñoz <gmunozfe@redhat.com>

jbpm-bpmn2/src/main/java/org/jbpm/bpmn2/xml/BoundaryEventHandler.java

@@ -59,7 +59,7 @@ public Object end(final String uri, final String localName,
         Node node = (Node) parser.getCurrent();
         String attachedTo = element.getAttribute("attachedToRef");
         Attr cancelActivityAttr = element.getAttributeNode("cancelActivity");
-        boolean cancelActivity = Boolean.parseBoolean(cancelActivityAttr.getValue());
+        boolean cancelActivity = cancelActivityAttr == null || Boolean.parseBoolean(cancelActivityAttr.getValue());
 
         // determine type of event definition, so the correct type of node can be generated
         org.w3c.dom.Node xmlNode = element.getFirstChild();