private List<String> readSpaceSeparatedAttribute(String attributeName, Element containingElement) {
        List<String> values=new ArrayList<>();
        String attributeString=nullIfEmpty(containingElement.getAttribute(attributeName));
        if (attributeString!=null) {
            for (String value : attributeString.split(" "))
                values.add(value);
        }
        return values;
    }
Returns the page element corresponding to the given node, never null
container-search/src/main/java/com/yahoo/search/pagetemplates/config/PageTemplateXMLReader.java