Add an optional filter for invalid (0 bpm) heart rate readings

src/main/java/de/dennisguse/opentracks/sensors/sensorData/AggregatorHeartRate.java

@@ -12,7 +12,9 @@ public class AggregatorHeartRate extends Aggregator<HeartRate, HeartRate> {
 
     @Override
     protected void computeValue(Raw<HeartRate> current) {
-        this.aggregatedValue = current.value();
+        if (current.value().isValid()) {
+            this.aggregatedValue = current.value();
+        }
     }
 
     @Override

src/main/java/de/dennisguse/opentracks/sensors/sensorData/SensorDataSet.java

@@ -64,7 +64,8 @@ public class SensorDataSet {
 
     public Pair<HeartRate, String> getHeartRate() {
         if (heartRate != null) {
-            return heartRate.getAggregatedValueWithSensorName(trackPointCreator.createNow());
+            Pair<HeartRate, String> value = heartRate.getAggregatedValueWithSensorName(trackPointCreator.createNow());
+            if (value.first.isValid()) return value;
         }
 
         return null;