public final Entry addEntry(Position inputPosition,Position outputPosition){
  Entry entry=new Entry(inputPosition,outputPosition);
  entries.add(entry);
  return entry;
}

public final Entry addEntry ( Position inputPosition , Position outputPosition ) { Entry entry = new Entry ( inputPosition , outputPosition ) ; entries . add ( entry ) ; return entry ; }
adds an entry to the source map ( entry must be added in order ) .
