You can retrieve a list of participants who are currently online and receiving all messages from an open channel using the
createParticipantListQuery() method. To retrieve a list of members in a group channel, call the
Members of a group channel are automatically updated when a user is online. But when a user is disconnected from the Sendbird server and then reconnected, you should call the
refresh() method to update the user's group channels with the latest information. See refresh all data related to a group channel for the sample code.