introduced caching method with default implementation in RankingMetric

java/com.sap.sailing.server/src/com/sap/sailing/server/masterdata/DummyTrackedRace.java

@@ -586,4 +586,10 @@ public class DummyTrackedRace extends TrackedRaceWithWindEssentials {
             WindPositionMode windPositionMode) {
         return null;
     }
+
+    @Override
+    public Distance getWindwardDistanceToOverallLeader(Competitor competitor, TimePoint timePoint,
+            WindPositionMode windPositionMode, WindLegTypeAndLegBearingCache cache) {
+        return null;
+    }
 }