code: public synchronized void addFile(String filename, String filePath) {
          // fix this to check if duplicate name exists.
          int fileIndex = fileNameList.indexOf(filename);
          if (fileIndex == -1) {
              fileNameList.add(filename);
              filePathList.add(filePath);
          }
      }
docs: Adds record of a new file, by filename and path.  The path
  may be relative to a source compilation path.
  
  @param fileName the filename to add, unqualified by path
  @param filePath the path for the filename, potentially relative
  to a source compilation path