Fix logical mistake.

git-svn-id: https://svn.apache.org/repos/asf/maven/maven-1/plugins/trunk@413947 13f79535-47bb-0310-9956-ffa450edef68

xdoc/src/plugin-resources/templates/downloads.jelly

@@ -45,7 +45,7 @@
              property is not defined -->
         <j:choose>
 
-          <j:when test="${context.getVariable('maven.xdoc.distributionUrl') != null and context.getVariable('maven.xdoc.distributionUrl') != ''}">
+          <j:when test="${context.getVariable('maven.xdoc.distributionUrl') == null or context.getVariable('maven.xdoc.distributionUrl') == ''}">
             <p>
               <message key="template.downloads.section.no_distURL1"
                     bundle="plugin-resources.templates.templates" />