Correctly detect missing arguments to Javadoc.

Submitted by:	 Peter Donald <donaldp@mad.scientist.com>


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@267791 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -448,7 +448,7 @@ public class Javadoc extends Exec {
     }
 
     public void execute() throws BuildException {
-        if (sourcePath == null && destDir == null ) {
+        if (sourcePath == null || destDir == null ) {
             String msg = "sourcePath and destDir attributes must be set!";
             throw new BuildException(msg);
         }