diff --git a/core/src/main/java/org/apache/struts2/dispatcher/SessionMap.java b/core/src/main/java/org/apache/struts2/dispatcher/SessionMap.java
index 60c2011aa..5a07e61de 100644
--- a/core/src/main/java/org/apache/struts2/dispatcher/SessionMap.java
+++ b/core/src/main/java/org/apache/struts2/dispatcher/SessionMap.java
@@ -103,10 +103,10 @@ public class SessionMap extends AbstractMap<String, Object> implements Serializa
             if (entries == null) {
                 entries = new HashSet<>();
 
-                Enumeration<?> enumeration = session.getAttributeNames();
+                Enumeration<String> enumeration = session.getAttributeNames();
 
                 while (enumeration.hasMoreElements()) {
-                    final String key = enumeration.nextElement().toString();
+                    final String key = enumeration.nextElement();
                     final Object value = session.getAttribute(key);
                     entries.add(new StringObjectEntry(key, value) {
                         @Override