server: fix scale vm with same disk offering id

Author: weizhouapache

server/src/main/java/com/cloud/vm/UserVmManagerImpl.java

@@ -2108,7 +2108,7 @@ protected void validateDiskOfferingChecks(ServiceOfferingVO currentServiceOfferi
             throw new InvalidParameterValueException("Unable to Scale VM, since disk offering strictness flag is not same for new service offering and old service offering");
         }
 
-        if (currentServiceOffering.getDiskOfferingStrictness() && currentServiceOffering.getDiskOfferingId() != newServiceOffering.getDiskOfferingId()) {
+        if (currentServiceOffering.getDiskOfferingStrictness() && !currentServiceOffering.getDiskOfferingId().equals(newServiceOffering.getDiskOfferingId())) {
             throw new InvalidParameterValueException("Unable to Scale VM, since disk offering id associated with the old service offering is not same for new service offering");
         }