set nfsVersion in ssvm agent.properties only if it is not null

Author: abh1sar

services/secondary-storage/controller/src/main/java/org/apache/cloudstack/secondarystorage/SecondaryStorageManagerImpl.java

@@ -1225,7 +1225,9 @@ public boolean finalizeVirtualMachineProfile(VirtualMachineProfile profile, Depl
             buf.append(" dns2=").append(dc.getDns2());
         }
         String nfsVersion = imageStoreDetailsUtil != null ? imageStoreDetailsUtil.getNfsVersion(secStores.get(0).getId()) : null;
-        buf.append(" nfsVersion=").append(nfsVersion);
+        if (nfsVersion != null) {
+            buf.append(" nfsVersion=").append(nfsVersion);
+        }
         buf.append(" keystore_password=").append(VirtualMachineGuru.getEncodedString(PasswordGenerator.generateRandomPassword(16)));
         String bootArgs = buf.toString();
         if (logger.isDebugEnabled()) {