Update Content app nullptrs

Author: lazarkov

examples/tv-app/android/App/platform-app/src/main/java/com/matter/tv/server/model/ContentApp.java

@@ -67,7 +67,7 @@ public void setEndpointId(int endpoint) {
   }
 
   public Set<SupportedCluster> getSupportedClusters() {
-    return Collections.unmodifiableSet(supportedClusters);
+    return supportedClusters != null ? Collections.unmodifiableSet(supportedClusters) : Collections.EMPTY_SET;
   }
 
   public String getVersion() {

examples/tv-app/android/App/platform-app/src/main/java/com/matter/tv/server/service/AppPlatformService.java

@@ -198,6 +198,7 @@ private Collection<ContentAppSupportedCluster> mapSupportedClusters(
       Collection<SupportedCluster> supportedClusters) {
     return supportedClusters
         .stream()
+        .filter(Objects::nonNull)
         .map(AppPlatformService::mapSupportedCluster)
         .collect(Collectors.toList());
   }