joinGroup method Null safety

Future<V2TimCallback> joinGroup(
  1. {required String groupID,
  2. required String message,
  3. String? groupType}
)

Join a group

Note:

Work group (Work): You cannot join the group actively, you can only invite the group by calling the V2TIMManager.getGroupManager().inviteUserToGroup() interface by group members. 
Public: After applying to join the group, the administrator needs to approve it. After receiving the V2TIMGroupListener -> onReceiveJoinApplication callback, the administrator calls the V2TIMManager.getGroupManager().getGroupApplicationList() interface to process the group join request. 
Other groups: You can join the group directly. 
Note: When on the web side, the groupType field is required when joining a live group

Implementation

Future<V2TimCallback> joinGroup({
  required String groupID,
  required String message,
  String? groupType,
}) async {
  return ImFlutterPlatform.instance
      .joinGroup(groupID: groupID, message: message, groupType: groupType);
}