Panic during code generation when using builder style interface + object in query parameters

Sorry for not putting together something to reproduce the issue:

I'm using the builder-style interface; an OpenAPI spec that I don't control has been updated to specify its query parameters as an object.

I'm hitting a panic here: https://github.com/oxidecomputer/progenitor/blob/9d88d24c6931887579e490d596d2e8b85e3f552a/progenitor-impl/src/method.rs#L1576-L1588

Message:  assertion `left == right` failed
  left: "my_object"
 right: "body"

I've tried patching the code generation locally to parameterize the codegen in this branch + remove the assertion - but I haven't had the time to understand the surrounding code yet (and if there's a reason for the assertion beyond "we don't expect any builders that aren't for the body").

Is this just a case of not having implemented https://github.com/oxidecomputer/progenitor/pull/1017 at the time the assertion was written?

The fix appears to be relatively straightforward but I'm struggling to get the time to think it through/follow it through - I just wanted to make sure that I wasn't missing something obvious.

Start at progenitor-impl/src/method.rs lines 1576-1588 and inspect the surrounding builder-style code generation. Compare the assertion with the changes discussed in pull request #1017, then verify that an object used in query parameters no longer causes a panic during generation.