Hmm, these lines just came along for the ride from rebasing off of https://github.com/twdb/hydropick/pull/69.  Some of the properties that are being serialized were introduced or reworked in that PR, so I opted to rebase on top of that rather than master. This PR also touches a lot of the same code as #69, so I wanted to avoid yet another complicated rebase (this PR has been rebased twice now). The downside is that this diff is harder to follow.

I don't mind re-rebasing if #69 still needs more work.