diff --git a/apps/showcase/src/main/resources/struts.xml b/apps/showcase/src/main/resources/struts.xml
index 373cf5f7b..eca6c6271 100644
--- a/apps/showcase/src/main/resources/struts.xml
+++ b/apps/showcase/src/main/resources/struts.xml
@@ -36,6 +36,12 @@
 
     <constant name="struts.allowlist.enable" value="true" />
     <constant name="struts.parameters.requireAnnotations" value="true" />
+    <constant name="struts.allowlist.classes"
+              value="
+                org.apache.struts2.showcase.conversion.OperationsEnum,
+                org.apache.struts2.showcase.conversion.Person,
+                org.apache.struts2.showcase.conversion.Address
+    "/>
 
     <constant name="struts.convention.package.locators.basePackage" value="org.apache.struts2.showcase" />
     <constant name="struts.convention.result.path" value="/WEB-INF" />