Type conversion escape hatch

I have an idea for some Liquibase type conversion features.  I’m not sure what order these are going to come out in. 

First, I would like a syntax–or an extra attribute, or something–that allows me to say in a dbms attribute set.  I end up having an explosion of changesets, the vast majority of which are duplicates (almost) of each other.

What do you think?

Best,
Laird