Yes. i think it should be blank. maybe you can try just adding an 'a' to the template. it won't matter it is only an 'a' or is empty. it will show what it's in that template, if the template is requested.
if you want eZ Publish take your extension template instead of ezflow template, you must place your extension after ezflow extension in the "active extensions" list (in override/site.ini.append.php) or edit extension.xml file to deal with dependencies between your extension and ezflow extension.
You may take a look at this thread to find more info
