VariantInfo: Added default value for platform unit observer

data/RobotAPI/VariantInfo-RobotAPI.xml

@@ -31,7 +31,8 @@
             memberName="platformUnitObserver"
             getterName="getPlatformUnitObserver"
             propertyName="PlatformUnitObserverName"
-            propertyIsOptional="false" />
+            propertyIsOptional="true"
+            propertyDefaultValue="PlatformUnitObserver" />
         <Proxy include="RobotAPI/interface/units/InertialMeasurementUnit.h"
             humanName="Inertial Measurement Unit Observer"
             typeName="InertialMeasurementUnitObserverInterfacePrx"