code: public String getTimestampVersion()
      {
          if ( timestampVersion == null )
          {
              if ( timestamp != null )
              {
                  assert isSnapshot();
                  SimpleDateFormat fmt = new SimpleDateFormat( "yyyyMMdd.HHmmss" );
                  fmt.setTimeZone( TimeZone.getTimeZone( "GMT" ) );
                  timestampVersion = MessageFormat.format( "{0}-{1}-{2}", new Object[]{
                      this.version.substring( 0, this.version.length() - "-SNAPSHOT".length() ),
                      fmt.format( new Date( timestamp.longValue() ) ), buildNumber } );
              }
              else
              {
                  timestampVersion = version;
              }
          }
          return timestampVersion;
      }
docs: Returns the timestamp version. <ul>
  <li>For release artifacts, this will be the same as {@link #getVersion()}.</li>
  <li>For non-timestamped SNAPSHOTS, this will be the same as {@link #getVersion()}.</li>
  <li>For timestamped SNAPSHOTS, this will be the timestamp version, i.e. the {@link #getVersion()} with
  <code>SNAPSHOT</code> replaced by {@link #getTimestampString()} and the {@link #getBuildNumber()} separated
  by a <code>-</code>.</li>
  </ul>
  
  @return the timestamp version.
  @since 1.0