code: public File asFile(String fileName) {
          File file = new File(fileName);
          try (FileOutputStream bos = new FileOutputStream(file)) {
              bos.write(data);
          } catch (IOException e) {
              throw new RuntimeException("unexpected error", e);
          }
          return file;
      }
docs: Writes the file data in the specified file and returns the final <code>File</code>.
  
  @param fileName the given file name, not null
  @return the final File, not null