mysql time-zone ambiguity?

[Gary Aitken]

mysql57-server installed;  When testing a jdbc connection I get:

The server time zone value 'MDT' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the 'serverTimezone' configuration property) to use a more specific time zone value if you want to utilize time zone support.

A diff says that /usr/share/zoneinfo/America/Denver is the same as /etc/localtime.

And the mysql time by default is set to 'SYSTEM':

garya at localhost [(none)]> select @@GLOBAL.time_zone, @@SESSION.time_zone;
+--------------------+---------------------+
| @@GLOBAL.time_zone | @@SESSION.time_zone |
+--------------------+---------------------+
| SYSTEM             | SYSTEM              |
+--------------------+---------------------+
1 row in set (0.00 sec)

on 11.4-RELEASE

Feels like the system is reporting the timezone as MDT and mysql wants something
like MDT/Denver?  I thought MDT was unique; Arizona is different.
Seems like this should default properly; ideas for what I have screwed up?
Also running ntpd if that matters.

Gary