GUI -- Made OOTB formatters and comparators final classes.

Change-Id: I0ea59bf92d97b6d104b7d3770fb5f2e93308bbdc
diff --git a/core/api/src/main/java/org/onosproject/ui/table/cell/IntComparator.java b/core/api/src/main/java/org/onosproject/ui/table/cell/IntComparator.java
index ddd90eb..c0d81ec 100644
--- a/core/api/src/main/java/org/onosproject/ui/table/cell/IntComparator.java
+++ b/core/api/src/main/java/org/onosproject/ui/table/cell/IntComparator.java
@@ -24,7 +24,10 @@
  * Note that null values are acceptable and are considered "smaller" than
  * any non-null value.
  */
-public class IntComparator extends AbstractCellComparator {
+public final class IntComparator extends AbstractCellComparator {
+
+    // non-instantiable
+    private IntComparator() { }
 
     @Override
     protected int nonNullCompare(Object o1, Object o2) {