Issue #2989261 by gugalamaciek, Leksat, sun, jcnventura, Mario Steinitz,...

                $account->set($property_name, ['target_id' => $file->id()]);

                break;

              case 'email':

                if ($property_name === 'mail') {

                  // The account email address is a very special user property,

                  // as it is one of the properties that requires to be unique

                  // for all Drupal users.

                  $account_by_mail = $this->userStorage->loadByProperties(['mail' => $claim_value]);

                  if (empty($account_by_mail) || ($account_by_mail->id() == $account->id())) {

                    $account->set('mail', $claim_value);

                  }

                  else {

                    $this->logger->warning('Could not save user info. Email address %email is already used in another account.',

                      ['%email' => $claim_value]);

                  }

                }

                else {

                  $account->set($property_name, $claim_value);

                }

                break;

              default:

                $this->logger->error('Could not save user info, property type not implemented: %property_type',

                  ['%property_type' => $property_type]