fixed test case so it won't consider null fixes for cache additions

java/com.sap.sailing.domain.test/src/com/sap/sailing/domain/test/WindEstimationOnConstructedTracksTest.java

@@ -105,7 +105,9 @@ public class WindEstimationOnConstructedTracksTest extends StoredTrackBasedTest
                     @Override
                     protected void cache(TimePoint timePoint, Wind fix) {
                         super.cache(timePoint, fix);
-                        cachedFixes.put(timePoint, fix);
+                        if (fix != null) {
+                            cachedFixes.put(timePoint, fix);
+                        }
                     }
         };
         Wind estimatedWindDirection = track.getEstimatedWind(/* position */ null, now);

java/com.sap.sailing.domain/src/com/sap/sailing/domain/tracking/impl/DynamicTrackedRaceImpl.java

@@ -232,7 +232,8 @@ public class DynamicTrackedRaceImpl extends TrackedRaceImpl implements
 
     @Override
     public void gpsFixReceived(GPSFix fix, Competitor competitor) {
-        if (getStart() == null || getStart().compareTo(fix.getTimePoint())>0) {
+        TimePoint start = getStart();
+        if (start == null || start.compareTo(fix.getTimePoint())>0) {
             // infer race start time from fix; earliest fix received defines start if earlier than assumed start so far
             setStartTimeReceived(fix.getTimePoint());
         }