code: public void update( Client client ) {
      RestfulUtils.update( ClientService.PATH, client, Client.class, super.httpClient );
    }
docs: This function updates the data of a client. To change only a specific attribute you can set this attribute in the update
  request. All other attributes that should not be edited are not inserted. You can only edit the description, email and credit
  card. The subscription can not be changed by updating the client data. This has to be done in the subscription call.
  @param client
  A {@link Client} with Id.