lms of this `formOrigin` using the related realms collection
   *
   * @param {string} formOrigin A form origin
   * @return {string[]} filteredRealms An array of domains related to the `formOrigin`
   * @async
   * @memberof LoginRelatedRealmsParent
   */
  async findRelatedRealms(formOrigin) {
    try {
      let formOriginURI = Services.io.newURI(formOrigin);
      let originDomain = formOriginURI.host;
      let [{ relatedRealms } = {}] =
        await this.getSharedCredentialsCollection();
      if (!relatedRealms) {
        return [];
      }
      let filterOriginIndex;
      let shouldInclude = false;
      let filteredRealms = relatedRealms.filter(_realms => {
        for (let relatedOrigin of _realms) {
          // We can't have an origin that matches multiple entries in our related realms collection
          // so we exit the loop early
          if (shouldInclude) {
            return false;
          }
          if (Services.eTLD.hasRootDomain(originDomain, relatedOrigin)) {
            shouldInclude = true;
            break;
          }
        }
        return shouldInclude;
      });
      // * Filtered realms is a nested array due to its structure in Remote Settings
      filteredRealms = filteredRealms.flat();

      filterOriginIndex = filteredRealms.indexOf(originDomain);
      // Removing the current formOrigin match if it exists in the related realms
      // so that we don't return duplicates when we search for logins
      if (filterOriginIndex !== -1) {
        filteredRealms.splice(filterOriginIndex, 1);
      }
      return filteredRealms;
    } catch (e) {
      lazy.log.error(e);
      return [];
    }
  }
}
PK