Check credentials type for null when saving

@@ -81,6 +81,9 @@ public class DeviceCredentialsServiceImpl extends AbstractEntityService implemen
     }
 
     private DeviceCredentials saveOrUpdate(TenantId tenantId, DeviceCredentials deviceCredentials) {
+        if (deviceCredentials.getCredentialsType() == null) {
+            throw new DataValidationException("Device credentials type should be specified");
+        }
         formatCredentials(deviceCredentials);
         log.trace("Executing updateDeviceCredentials [{}]", deviceCredentials);
         credentialsValidator.validate(deviceCredentials, id -> tenantId);