[Terry N.] make field final

src/java/org/web3d/vrml/nodes/SceneGraphTraverser.java

@@ -39,7 +39,7 @@ public class SceneGraphTraverser {
     private boolean inUse;
 
     /** Temporary map during traversal for use references */
-    private HashSet<VRMLNodeType> usedNodes;
+    private final HashSet<VRMLNodeType> usedNodes;
 
     /** The detailObs for the scene graph */
     private SceneGraphTraversalDetailObserver detailObs;