code: function updateCustomProperty($mailingId, $property) {
  
          $queryParameters = array(
              'name' => $property->key,
              'value' => $property->value
          );
  
          return $this->put("mailings/${mailingId}/settings/properties", "", $queryParameters);
      }
docs: Updates a custom property of the mailing with the provided id.
  
  @param int $mailingId
  @param com_maileon_api_mailings_CustomProperty $property
  @return com_maileon_api_MaileonAPIResult