make instance variable final

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1779551 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/poi/ss/usermodel/PageOrder.java

@@ -34,7 +34,7 @@ public enum PageOrder {
     OVER_THEN_DOWN(2);
 
 
-    private int order;
+    private final int order;
 
 
     private PageOrder(int order) {