code: function toUnusableRecordBFK(recordState) {
    // if (!hasUnusableRecordIdentifier(recordState)) {
    //   return undefined;
    // }
    const md5s = recordState.md5s;
    return [
      trimOrEmpty(recordState.eventID), trimOrEmpty(recordState.eventSeqNo), trimOrEmpty(recordState.eventSubSeqNo),
      trimOrEmpty(md5s && md5s.userRec), trimOrEmpty(md5s && md5s.rec), trimOrEmpty(md5s && md5s.data)
    ].join('|');
  }
docs: Creates a BFK (i.e. Big Fat Key) for the given unusable record state using EVERY available id, key and
  sequence number property.
  @param {UnusableRecordState} recordState - the tracked state of an unusable record
  @returns {string|undefined} an "over-the-top key" for matching purposes