javadoc doesn't like the palckage name '', skip it

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@377942 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -2136,6 +2136,13 @@ public class Javadoc extends Task {
                     });
 
                 if (files.length > 0) {
+                    if ("".equals(dirs[i])) {
+                        log(baseDir
+                            + " contains source files in the default package,"
+                            + " you must specify them as source files"
+                            + " not packages.",
+                            Project.MSG_WARN);
+                    } else {
                     containsPackages = true;
                     String packageName =
                         dirs[i].replace(File.separatorChar, '.');
@@ -2143,6 +2150,7 @@ public class Javadoc extends Task {
                         addedPackages.addElement(packageName);
                         pn.addElement(packageName);
                     }
+                    }
                 }
             }
             if (containsPackages) {