Looks fine, two things stand out though.

1. Before it was expected that parameters like ports and addresses would be define while the client is running. This isn't true anymore so it may brake some things making that assumptions. Usually testing if that?
2. You don't have any tests for the new behaviour. You'll need a few to demostrate the lazy feature along with making sure it works as expected and for catching future regressions.

Need to be redone in the future, more considerations must be made as the API will actually change if the PolykeyClient is lazy. We should probably just make 2 separate classes instead for lazy + non-lazy respectively.