public Pair<InputDocument,List<InputDocument>> selectSample(List<InputDocument> documents,int n){
  int i=random.nextInt(documents.size());
  InputDocument testDoc=documents.get(i);
  List<InputDocument> others=filter(documents,null);
  List<InputDocument> corpusSubset=getRandomDocuments(others,n);
  return new Pair<>(testDoc,corpusSubset);
}

public Pair < InputDocument , List < InputDocument > > selectSample ( List < InputDocument > documents , int n ) { int i = random . nextInt ( documents . size ( ) ) ; InputDocument testDoc = documents . get ( i ) ; List < InputDocument > others = filter ( documents , null ) ; List < InputDocument > corpusSubset = getRandomDocuments ( others , n ) ; return new Pair < > ( testDoc , corpusSubset ) ; }
select one document at random , then n others w / o replacement as corpus
