code: public String extractType(XAttribute attribute) {
  		XAttribute attr = attribute.getAttributes().get(KEY_TYPE);
  		if (attr == null) {
  			return null;
  		} else {
  			return ((XAttributeLiteral) attr).getValue();
  		}
  	}
docs: Retrieves the cost type for an attribute, if set by this extension's type
  attribute.
  
  @param attribute
  Attribute element to retrieve cost type for.
  @return The requested cost type.