georeferencing - Can I define a transformation between 2D and 3D in Geotools?

I'm using Geotools, and I need to convert coordinates between 2D and 3D coordinate reference systems. I recognize that there's no universally-correct way to do this: 2D -> 3D means "making up" a Z coordinate, and 3D -> 2D means losing information. But, is there some way to teach Geotools that, in my particular context, I want to use a specific transformation. E.g.:

+-----+                 +-----+
|     | --- Z = 15 ---> |     |
| 2D  |                 |  3D |
|     | <-- drop Z ---- |     |
+-----+                 +-----+

I know I can transform any particular coordinate manually this way, but I'd like to integrate it so this Just Works. e.g. I can do CRS.findMathTranform(a, b) and if a is convertible to my 2D CRS, and my 3D CRS is convertible to b, it works.