public QLFDocument(List<F> list,String docno,Map<String,String> extraProps){
  featureList=new MemoryLocalFeatureList<F>(list);
  iterator=list.iterator();
  if (extraProps != null)   props.putAll(extraProps);
  props.put("docno",docno);
}

public QLFDocument ( List < F > list , String docno , Map < String , String > extraProps ) { featureList = new MemoryLocalFeatureList < F > ( list ) ; iterator = list . iterator ( ) ; if ( extraProps != null ) props . putAll ( extraProps ) ; props . put ( "docno" , docno ) ; }
construct a new qlfdocument instance from the contents of the given feature list .
