Is there some undocumented technique to get the jdk installer
to actually put the src code in some known location in an
unzipped format preferrably?  There's an install option
for the src but it appears to be disabled or read only as
clicking on the options has no discernable effect.

I'll probably download the src separately and install from that
though it's not really going to match the jdk version exactly.
But it'd be nice in the future to know what the trick is.