public boolean start(Writer writer) { boolean result = super.start(writer); if (this.label == null && (href == null)) { if ((rootNodeAttr == null) || (childCollectionProperty == null) || (nodeTitleProperty == null) || (nodeIdProperty == null)) { fieldError("label","The TreeTag requires either a value for 'label' or 'href' or ALL of 'rootNode', " + "'childCollectionProperty', 'nodeTitleProperty', and 'nodeIdProperty'", null); } } return result; }