docs: private String guessImageFormat(String contentType, String imagePath) throws IOException {
  
          String format = "png";
  
          if (contentType == null) {
              contentType = URLConnection.guessContentTypeFromName(imagePath);
          }
  
          if (contentType != null) {
              format = contentType.replaceFirst("^image/([^;]+)[;]?.*$", "$1");
          }
          else {
              int queryStringIndex = imagePath.indexOf('?');
  
              if (queryStringIndex != -1) {
                  imagePath = imagePath.substring(0, queryStringIndex);
              }
  
              String[] pathTokens = imagePath.split("\\.");
  
              if (pathTokens.length > 1) {
                  format = pathTokens[pathTokens.length - 1];
              }
          }
  
          return format;
      }