Add forgotten exception cause

(cherry picked from commit 2377d62)

repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/work/segmentation/WorkSegmentationStrategyFactory.java

@@ -69,7 +69,7 @@ public WorkSegmentationStrategy createStrategy(TaskWorkManagementType configurat
 					PrismContext.class);
 			return constructor.newInstance(configuration, prismContext);
 		} catch (NoSuchMethodException | IllegalAccessException | InstantiationException | InvocationTargetException e) {
-			throw new SystemException("Couldn't instantiate work bucket segmentation strategy " + strategyClass + " for " + configuration);
+			throw new SystemException("Couldn't instantiate work bucket segmentation strategy " + strategyClass + " for " + configuration, e);
 		}
 	}