Mark field final (not strictly required, but looks better)

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@830859 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/taskdefs/Redirector.java

@@ -176,7 +176,7 @@ public class Redirector {
     private boolean appendProperties = true;
 
     /** The thread group used for starting <code>StreamPumper</code> threads */
-    private ThreadGroup threadGroup = new ThreadGroup("redirector");
+    private final ThreadGroup threadGroup = new ThreadGroup("redirector");
 
     /** whether to log the inputstring */
     private boolean logInputString = true;