wml dom wml WMLDoElement wmldoelementimpl wmlelementimpl wmldoelement serialversionuid l wmldoelementimpl wmldocumentimpl owner tagname owner tagname setoptional newvalue newvalue getoptional newvalue newvalue setxmllang newvalue newvalue getxmllang setid newvalue newvalue getid newvalue newvalue settype newvalue newvalue gettype newvalue newvalue