Add missing HashSet import in LibvirtStorageAdaptor

Author: Gean Jair Silva

plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/storage/LibvirtStorageAdaptor.java

@@ -27,6 +27,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.HashSet;
 import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.stream.Collectors;