code: public String toFilename() {
          if (m_filename == null) { // lazily convert, since not always needed
              m_filename = m_normalized.replaceAll(":", "_");
              if (m_filename.endsWith(".")) {
                  m_filename =
                          m_filename.substring(0, m_filename.length() - 1) + "%";
              }
          }
          return m_filename;
      }
docs: Return a string representing this PID that can be safely used as a
  filename on any OS.
  <ul>
  <li> The colon (:) is replaced with an underscore (_).</li>
  <li> Trailing dots are encoded as percents (%).</li>
  </ul>