code: private synchronized File getWorkingDirectory() {
      if (workingDirectory == null) {
        try {
          workingDirectory =
              Files.createTempDirectory(TEMP_DIRECTORY_PREFIX).toFile();
        } catch (IOException e) {
          throw new UnexpectedException(e);
        }
      }
      return workingDirectory;
    }
docs: Gets the working directory, creating a temporary one if one was not
  specified during construction.
  @return The working directory.