question: public void addNodesInDocOrder ( DTMIterator iterator , XPathContext support ) { if ( ! m_mutable ) throw new RuntimeException ( XSLMessages . createXPATHMessage ( XPATHErrorResources . ER_NODESETDTM_NOT_MUTABLE , null ) ) ; int node ; while ( DTM . NULL != ( node = iterator . nextNode ( ) ) ) { addNodeInDocOrder ( node , support ) ; } }
target:  Copy NodeList members into this nodelist, adding in document order.  If a node is null, don't add it.