code: function createCompositeKeyString(rec) {
      const cKey = createCompositeKey(rec);
      return rec.hasDynamicPath
          ? cKey.id +
              Object.keys(cKey)
                  .filter(k => k !== "id")
                  .map(k => `::${k}:${cKey[k]}`)
          : rec.id;
  }
docs: Creates a string based composite key if the passed in record
  has dynamic path segments; if not it will just return the "id"