Fix null on putAll

Author: BryanMLima

engine/storage/volume/src/main/java/org/apache/cloudstack/storage/datastore/provider/DefaultHostListener.java

@@ -58,6 +58,7 @@
 
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 
 public class DefaultHostListener implements HypervisorHostListener {
     protected Logger logger = LogManager.getLogger(getClass());
@@ -130,8 +131,9 @@ private NicTO createNicTOFromNetworkAndOffering(NetworkVO networkVO, NetworkOffe
     public boolean hostConnect(long hostId, long poolId) throws StorageConflictException {
         StoragePool pool = (StoragePool) this.dataStoreMgr.getDataStore(poolId, DataStoreRole.Primary);
         Map<String, String> detailsMap = storagePoolDetailsDao.listDetailsKeyPairs(poolId);
-        detailsMap.putAll(storageManager.getStoragePoolNFSMountOpts(pool, null).first());
+        Map<String, String> nfsMountOpts = storageManager.getStoragePoolNFSMountOpts(pool, null).first();
 
+        Optional.ofNullable(nfsMountOpts).ifPresent(detailsMap::putAll);
         ModifyStoragePoolCommand cmd = new ModifyStoragePoolCommand(true, pool, detailsMap);
         cmd.setWait(modifyStoragePoolCommandWait);