Dave, it's the latter, it came with a "7-way blade" which is round.
I'm the second owner and the first tells me he made no modifications.

However my on-site engineer (who goes by "Dad") sent me the following
report this morning:

snip
The problem I had this morning was with the 7/4-pin adapter. That
sucker did not have the common wire connected thru from the 4-pin plug
to the 7-pin plug. Ordinarily that should not be a problem PROVIDED
the trailer is physically hitched to the tow car--the system uses
chassis metal for the common return. But I did not have a physical
connection this morning, only the electrical connection. This evening,
when I jumpered the common lead through from the 4-pin to the 7-pin,
everything worked like the factory said it should (but not like that
wiring diagram you found on the net this morning). The upper (amber)
lamp is the turn signal, the middle (red) lamp is the brake, and the
lower (red) is the tail light.

So I made the change that Mac described. Removed the lead from the
brake lamp and taped it off. Switched the lead from the turn lamp to
the brake lamp (in the 4-pin system, that serves as both brake and
turn signal). Then I gave it a full test. Tail only, tail and turn,
brake only, brake and turn, and brake, tail, and turn. Everyting now
works like it should in a 4-pin setup with my van.
/snip

Thanks to everyone for the feedback on this topic. I'll be prepared
for the new trailer this summer!

2NO