docs: @Trivial
      public static String toAbsSec(long nano, int padLeft) {
          if ( nano < 0 ) {
              return "-" + toAbsSec(-1 * nano, padLeft);
          } else if ( nano == 0 ) {
              return PAD.substring(0, padLeft) + "." + PAD.substring(PAD_RIGHT);
          }
  
          String nanoText = Long.toString(nano);
          int nanoDigits = nanoText.length();
  
          if ( nanoDigits > NANO_IN_ONE_DIGITS ) { // greater than 999,999,999
              int secDigits = nanoDigits - NANO_IN_ONE_DIGITS;
              if ( secDigits >= padLeft ) {
                  return nanoText.substring(0, secDigits) +
                         "." +
                         nanoText.substring(secDigits, secDigits + PAD_RIGHT);
              } else {
                  int padDigits = padLeft - secDigits;
                  if ( padDigits > PAD_LEN ) {
                      padDigits = PAD_LEN;
                  }
                  return PAD.substring(0, padDigits) + nanoText.substring(0, secDigits) +
                         "." +
                         nanoText.substring(secDigits, secDigits + PAD_RIGHT);
              }
  
          } else if ( nanoDigits > (NANO_IN_ONE_DIGITS - PAD_RIGHT) ) { // less than 1,000,000,000 and greater than 999
              if ( padLeft > PAD_LEN ) {
                  padLeft = PAD_LEN;
              }
              int missingDigits = NANO_IN_ONE_DIGITS - nanoDigits;
              return PAD.substring(0, padLeft) +
                     "." +
                     PAD.substring(0, missingDigits) + nanoText.substring(0, PAD_RIGHT - missingDigits);
  
          } else { // less than 1,000, but greater than 0.
              if ( padLeft > PAD_LEN ) {
                  padLeft = PAD_LEN;
              }
              return PAD.substring(0, padLeft) +
                     "." +
                     PAD.substring(PAD_RIGHT - 1) + "*";
          }
      }