Fixed an example

Author: exec-astraea

content/en/docs/refguide/installation/upgrading-from-10-to-11.md

@@ -146,7 +146,7 @@ In this example, Mendix will handle string concatenation correctly no matter if
 In this particular example, if you want to prevent the generation of email addresses without the first part you should add a validation check before doing concatenation: 
 
 ```
-if trim($User/Name) = '' then $User/Name + "@mendix.com" else ''
+if trim($User/Name) = '' then '' else $User/Name + "@mendix.com"
 ```
 
 ### Using the **ShowHomePage** Microflow in the **System** Module {#apply-entity-access}