EMS: Control Service: Changed TopicBeacon to *not* send prediction or...

EMS: Control Service: Changed TopicBeacon to *not* send prediction or slo-violation-detector events, if they are going to be empty

event-management/control-service/src/main/java/eu/melodic/event/control/util/TopicBeacon.java

@@ -167,6 +167,12 @@ public class TopicBeacon implements InitializingBean {
         }).collect(Collectors.toList());
         log.debug("Topic Beacon: Transmitting Prediction info: Metric Contexts in event format: {}", payload);
 
+        // Skip event sending if payload is empty
+        if (payload.size()==0) {
+            log.debug("Topic Beacon: Transmitting Prediction info: Event is empty. Not sending anything");
+            return;
+        }
+
         String eventPayload = gson.toJson(payload);
 
         log.debug("Topic Beacon: Transmitting Prediction info: event={}, topics={}", eventPayload, beaconPredictionTopics);
@@ -189,6 +195,12 @@ public class TopicBeacon implements InitializingBean {
             return;
         log.debug("Topic Beacon: transmitSloViolatorInfo: SLO metric decompositions: {}", sloMetricDecompositions);
 
+        // Skip event sending if payload is empty
+        if (!(sloMetricDecompositions instanceof Map) || ((Map) sloMetricDecompositions).size() == 0) {
+            log.debug("Topic Beacon: transmitSloViolatorInfo: Event is empty. Not sending anything");
+            return;
+        }
+
         String eventPayload = gson.toJson(sloMetricDecompositions);
 
         log.debug("Topic Beacon: Transmitting SLO Violator info: event={}, topics={}", eventPayload, beaconSloViolationDetectorTopics);