set @start_value = @@wsrep_node_name;
set @@global.wsrep_node_name='test';
set @@global.wsrep_node_name=NULL;
SET @@global.wsrep_node_name = 1;
ERROR 42000: Incorrect argument type to variable 'wsrep_node_name'
set @@global.wsrep_node_name = @start_value;