java: Adding final modifier for a constant

Author: barancev

java/client/src/org/openqa/selenium/support/ui/FluentWait.java

@@ -67,7 +67,7 @@
  */
 public class FluentWait<T> implements Wait<T> {
 
-  public static Duration FIVE_HUNDRED_MILLIS = new Duration(500, MILLISECONDS);
+  public static final Duration FIVE_HUNDRED_MILLIS = new Duration(500, MILLISECONDS);
 
   private final T input;
   private final Clock clock;