Index: maven-i18n-plugin/src/java/org/codelutin/i18n/plugin/util/SortedProperties.java
diff -u maven-i18n-plugin/src/java/org/codelutin/i18n/plugin/util/SortedProperties.java:1.3 maven-i18n-plugin/src/java/org/codelutin/i18n/plugin/util/SortedProperties.java:1.4
--- maven-i18n-plugin/src/java/org/codelutin/i18n/plugin/util/SortedProperties.java:1.3	Fri Nov  2 16:06:37 2007
+++ maven-i18n-plugin/src/java/org/codelutin/i18n/plugin/util/SortedProperties.java	Thu Feb  7 12:56:04 2008
@@ -19,6 +19,8 @@
 
 package org.codelutin.i18n.plugin.util;
 
+import org.codelutin.util.CollectionUtil;
+
 import java.util.Collections;
 import java.util.Enumeration;
 import java.util.List;
@@ -27,14 +29,13 @@
 
 /**
  * Permet d'avoir les fichiers de propriétés triés.
- * 
- * @author julien
  *
+ * @author julien
  */
 public class SortedProperties extends Properties {
 
     private static final long serialVersionUID = 1L;
-    
+
     public SortedProperties() {
         super();
     }
@@ -43,12 +44,19 @@
         super(defaults);
     }
 
+    @Override
     public synchronized Enumeration<Object> keys() {
-        Enumeration enumeration = super.keys();
-        
-        List list = Collections.list(enumeration);
-        Collections.sort(list);
-        
-        return new Vector(list).elements();
+        List<Object> objects = Collections.list(super.keys());
+        Vector<Object> result;
+        try {
+            List<Comparable> list = CollectionUtil.toGenericList(objects, Comparable.class);
+            Collections.sort(list);
+            result = new Vector<Object>(list);
+        } catch (IllegalArgumentException e) {
+            // keys are not comparable !!!
+            // can not sort keys
+            result = new Vector<Object>(objects);
+        }
+        return result.elements();
     }
 }