You need to declare process variables(properties) in your process to be able to use them:
...
<bpmn2:itemDefinition id="_xItem" structureRef="java.lang.Boolean"/>
<bpmn2:process id="PrasDemo" drools:packageName="SDS" name="PrasDemo" isExecutable="true">
<bpmn2:property id="result" itemSubjectRef="_xItem"/>
...
that should do the trick and your XOR gateway will work properly.
HTH