code: public static String replaceChecksum(final String contentSpecString, final String checksum) {
          Matcher matcher = CS_CHECKSUM_PATTERN.matcher(contentSpecString);
          if (matcher.find()) {
              return matcher.replaceFirst("CHECKSUM=" + checksum + "\n");
          }
  
          return contentSpecString;
      }
docs: Replaces the checksum of a Content Spec with a new checksum value
  
  @param contentSpecString The content spec to replace the checksum for.
  @param checksum          The new checksum to be set in the Content Spec.
  @return The fixed content spec string.