add null check in constructor to initialize excluded services as empt…

…y set

ranger-core/src/main/java/io/appform/ranger/core/finderhub/ServiceFinderHub.java

@@ -103,7 +103,7 @@ public ServiceFinderHub(
                                                       Collections.emptyList(),
                                       10_000));
         this.refresherPool = createRefresherPool();
-        this.excludedServices = excludedServices;
+        this.excludedServices = Objects.requireNonNullElseGet(excludedServices, Set::of);
     }
 
     public Optional<ServiceFinder<T, R>> finder(final Service service) {