code: private function writeComment(Worksheet $pSheet, $coordinate)
      {
          $result = '';
          if (!$this->isPdf && isset($pSheet->getComments()[$coordinate])) {
              $result .= '<a class="comment-indicator"></a>';
              $result .= '<div class="comment">' . nl2br($pSheet->getComment($coordinate)->getText()->getPlainText()) . '</div>';
              $result .= PHP_EOL;
          }
  
          return $result;
      }
docs: Write a comment in the same format as LibreOffice.
  
  @see https://github.com/LibreOffice/core/blob/9fc9bf3240f8c62ad7859947ab8a033ac1fe93fa/sc/source/filter/html/htmlexp.cxx#L1073-L1092
  
  @param Worksheet $pSheet
  @param string $coordinate
  
  @return string