ports: how to handle 'alternate' dependencies

[John W]

I'm just learning the guts of how ports work, and wonder:

How do ports specify that "any one of X, Y, Z " would satisfy a dependency.

For instance, when I build graphics/jalbum, it says it requires jdk16.
I would rather use diablo-jdk16, since I find it faster and it is
easier to install.

But how would I alter graphics/jalbum to say, essentially, "either
jdk16 or diablo-jdk16 is required"

Generally, how to handle the case when a port requires X, but there
are multiple implementations of X that can perform the job, and any
will suffice?
I feel like this issue must come up from time to time, what is the
right way to deal with it?
I didn't see any mention of this in the porters handbook...

Thanks
-John