Index: trunk/src/org/openstreetmap/josm/gui/preferences/advanced/PrefEntry.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/preferences/advanced/PrefEntry.java	(revision 9905)
+++ trunk/src/org/openstreetmap/josm/gui/preferences/advanced/PrefEntry.java	(revision 9906)
@@ -105,4 +105,26 @@
 
     @Override
+    public int hashCode() {
+        return 31 + ((key == null) ? 0 : key.hashCode());
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        PrefEntry other = (PrefEntry) obj;
+        if (key == null) {
+            if (other.key != null)
+                return false;
+        } else if (!key.equals(other.key))
+            return false;
+        return true;
+    }
+
+    @Override
     public String toString() {
         return value.toString();