When set at runtime, wsrep_sst_method accepts any value

MariaDB [(none)]> set global wsrep_sst_method := 'handwrite rows and send them via post';

Query OK, 0 rows affected (0.000 sec)

MariaDB [(none)]> select @@wsrep_sst_method;

+---------------------------------------+

| @@wsrep_sst_method                    |

+---------------------------------------+

| handwrite rows and send them via post |

+---------------------------------------+

1 row in set (0.000 sec)