In Galera Cluster, when init gtid does not get domain_id and server_id from mariadb.cnf

1. sql\wsrep_mysqld.cc
void wsrep_init_globals()
{
wsrep_gtid_server.domain_id= wsrep_gtid_domain_id;
wsrep_init_sidno(Wsrep_server_state::instance().connected_gtid().id());
wsrep_init_gtid();
......

void wsrep_init_gtid()
{
wsrep_server_gtid_t stored_gtid= wsrep_get_SE_checkpoint<wsrep_server_gtid_t>();
if (stored_gtid.server_id == 0)
{
rpl_gtid wsrep_last_gtid;
stored_gtid.domain_id= wsrep_gtid_server.domain_id;
if (mysql_bin_log.is_open() &&
mysql_bin_log.lookup_domain_in_binlog_state(stored_gtid.domain_id,
&wsrep_last_gtid))

{ stored_gtid.server_id= wsrep_last_gtid.server_id; stored_gtid.seqno= wsrep_last_gtid.seq_no; }

else

{ stored_gtid.server_id= global_system_variables.server_id; stored_gtid.seqno= 0; }

}
wsrep_gtid_server.gtid(stored_gtid);
}

2. sql\wsrep_xid.cc
template<>
wsrep_server_gtid_t wsrep_get_SE_checkpoint()
{
XID xid;
wsrep_server_gtid_t gtid=

{0,0,0}

;

if (!wsrep_get_SE_checkpoint_common(xid))

{ return gtid; }

if (xid.data[WSREP_XID_VERSION_OFFSET] == WSREP_XID_VERSION_3)

{ memcpy(&gtid, &xid.data[WSREP_XID_RPL_GTID_OFFSET], sizeof(wsrep_server_gtid_t)); }

return gtid;
}

3. In function wsrep_get_SE_checkpoint, domain_id and server_id were from engine, and were set to gtid.
In function wsrep_init_gtid , stored_gtid.server_id was not equal to 0. But domain_id and server_id in mariadb.cnf were not same as stored_id.

4. Backup data from cluster1 with mariabackup, and then restore data to cluster2. So the GTID domain_id and server_id become same.
GTID : <domain_id> - <server_id> - <seqno>