Allow sub classes of Zip to hold their own filesets and not tell Zip

about it.

This one enables War to build .war files without content included in
extra filesets.


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@268034 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -132,7 +132,7 @@ public class Zip extends MatchingTask {
     }
 
     public void execute() throws BuildException {
-        if (baseDir == null && filesets.size() == 0)
+        if (baseDir == null && filesets.size() == 0 && "zip".equals(archiveType))
             throw new BuildException("basedir attribute must be set, or at least one fileset must be given!");
 
         Vector dss = new Vector ();