TO_DATE: 'J' format element not supported and not listed as unsupported

In Oracle, TO_DATE allows 'J' (Julian day; the number of days since January 1, 4712 BC).
In MariaDB it does not work, and it is not listed in the commit comment either as a supported or unsupported element. Maybe it results from BC not being supported, which the comment does say; in this case, it's just a documentation issue – I think all unsupported formats need to be explicitly listed, to avoid confusion.

MariaDB [test]> SELECT TO_DATE('1721426','J') AS x;

ERROR 3047 (HY000): Invalid argument error: date format not recognized at J in function to_date.

SELECT TO_DATE('1721426','J') AS x;

X

03-JAN-01