Wrong results from st_isvalid or st_validate function, while using multipolygon

MariaDB [test]> select ST_isvalid(ST_GEOMFROMTEXT('multipolygon(((28 26,28 0,84 0,84 42,28 26),(52 18,66 23,73 9,48 6,52 18)), ((59 18,67 18,67 13,59 13,59 18)))')) a;

+------+

| a    |

+------+

|    0 |

+------+

1 row in set (0,002 sec)

MariaDB [test]>  select ST_isvalid(ST_GEOMFROMTEXT(' MULTIPOLYGON((( 0 0, 6 0, 1 2, 0 0)), (( 7 7, 1 8, 7 0, 7 7 ))) ')) a;

+------+

| a    |

+------+

|    0 |

+------+

1 row in set (0,002 sec)

MariaDB [test]>  select ST_VALIDATE(ST_GEOMFROMTEXT(' MULTIPOLYGON((( 0 0, 6 0, 1 2, 0 0)), (( 7 7, 1 8, 7 0, 7 7 ))) ')) a;

+------+

| a    |

+------+

| NULL |

+------+

1 row in set (0,002 sec)

MariaDB [test]> select ST_VALIDATE(ST_GEOMFROMTEXT('multipolygon(((28 26,28 0,84 0,84 42,28 26),(52 18,66 23,73 9,48 6,52 18)), ((59 18,67 18,67 13,59 13,59 18)))')) a;

+------+

| a    |

+------+

| NULL |

+------+

1 row in set (0,002 sec)

mysql> select ST_isvalid(ST_GEOMFROMTEXT('multipolygon(((28 26,28 0,84 0,84 42,28 26),(52 18,66 23,73 9,48 6,52 18)), ((59 18,67 18,67 13,59 13,59 18)))')) a;

+------+

| a    |

+------+

|    1 |

+------+

1 row in set (0,00 sec)

mysql>  select ST_isvalid(ST_GEOMFROMTEXT(' MULTIPOLYGON((( 0 0, 6 0, 1 2, 0 0)), (( 7 7, 1 8, 7 0, 7 7 ))) ')) a;

+------+

| a    |

+------+

|    1 |

+------+

1 row in set (0,00 sec)