Remove an unnecessary method call.

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@277319 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -155,8 +155,7 @@ public class Length extends Task {
             String[] f = ds.getIncludedFiles();
             for (int j = 0; j < f.length; j++) {
                 File file = FileUtils.getFileUtils().resolveFile(basedir, f[j]);
-                if (!(included.contains(file))) {
-                    included.add(file);
+                if (included.add(file)) {
                     h.handle(file);
                 }
             }