code: public com.google.api.ads.adwords.axis.v201809.rm.UserIdentifier[] getUserIdentifiers() {
          return userIdentifiers;
      }
docs: Gets the userIdentifiers value for this StoreSalesTransaction.
  
  @return userIdentifiers   * List of UserIdentifiers.
  <span class="constraint Required">This field is required
  and should not be {@code null}.</span>