Output result in show create table for mysql_json type should be longtext

MariaDB [mysql_data_json]> CREATE TABLE testjson (t mysql_json NOT NULL);

ERROR 4161 (HY000): Unknown data type: 'mysql_json'

MariaDB [mysql_data_json]> install soname 'type_mysql_json';

Query OK, 0 rows affected (0.015 sec)

MariaDB [mysql_data_json]> CREATE TABLE testjson (t mysql_json NOT NULL);

Query OK, 0 rows affected (0.031 sec)

MariaDB [mysql_data_json]> show create table testjson;

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

| Table    | Create Table                                                                                                                                                             |

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

| testjson | CREATE TABLE `testjson` (

  `t` json /* MySQL 5.7 */ CHARACTER SET utf8mb4 COLLATE utf8mb4_bin NOT NULL

) ENGINE=InnoDB DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci |

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

1 row in set (0.000 sec)

CREATE TABLE `t2` (

    ->   `j` json CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL CHECK (json_valid(`j`))

    -> ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL CHECK (json_valid(`j`)...' at line 2