code: func (m *Manager) AllByClientID(clientID string) (clients []*Oauth2Client, err error) {
  	clients = make([]*Oauth2Client, 0)
  
  	err = m.getClientsCollection().Find(bson.M{"clientid": clientID}).All(&clients)
  	return
  }
docs: //AllByClientID retrieves all clients with a given ID