fixes NPE on iterator causing JXPath to fail with exception if expression returns no results

PR: 20272
Submitted by: Nick Chalko (nick at chalko dot com)


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@274648 13f79535-47bb-0310-9956-ffa450edef68

proposal/embed/src/java/org/apache/tools/ant/taskdefs/optional/JXPath.java

@@ -129,7 +129,7 @@ public class JXPath extends Task {
 
             Iterator iter = jxpathCtx.iterate(name);
 
-            if(iter==null){
+            if(iter==null||!iter.hasNext()){
                 return "null";
             }