OPENJPA-536. Checking in optimization on behalf of Amy Yang.

git-svn-id: https://svn.apache.org/repos/asf/openjpa/branches/1.1.x@650703 13f79535-47bb-0310-9956-ffa450edef68

openjpa-kernel/src/main/java/org/apache/openjpa/meta/InheritanceOrderedMetaDataList.java

@@ -31,6 +31,8 @@ public class InheritanceOrderedMetaDataList
     private LinkedList<ClassMetaData> buffer = new LinkedList<ClassMetaData>();
 
     public boolean add(ClassMetaData meta) {
+        if (meta == null || buffer.contains(meta))
+            return false;
         for (ListIterator<ClassMetaData> itr = buffer.listIterator();
             itr.hasNext();) {
             int ord = _comp.compare(meta, itr.next());