Element enumeration = XUtil.getFirstChildElement(attribute, "enumeration");
if (attrType.equals("NMTOKEN") && enumeration != null) {
out.print('(');
Element literal = XUtil.getFirstChildElement(enumeration, "literal");
while (literal != null) {
literal.normalize();
Node literalValueNode = getFirstChildOfType(literal, Node.TEXT_NODE);
String literalValue = literalValueNode != null
? literalValueNode.getNodeValue() : "";
out.print(literalValue);
literal = XUtil.getNextSiblingElement(literal, "literal");