question: public static List < ? extends Element > childElementList ( Element element , Set < String > childElementNames ) { if ( element == null ) return null ; List < Element > elements = new LinkedList < Element > ( ) ; if ( childElementNames == null ) return elements ; Node node = element . getFirstChild ( ) ; if ( node != null ) { do { if ( node . getNodeType ( ) == Node . ELEMENT_NODE && childElementNames . contains ( node . getNodeName ( ) ) ) { Element childElement = ( Element ) node ; elements . add ( childElement ) ; } } while ( ( node = node . getNextSibling ( ) ) != null ) ; } return elements ; }
target:  Return a List of Element objects that have the given name and are immediate children of the given element; if name is null, all child elements will be included. 