Allow Interceptors to add EventListeners.

[yschimke]

#fixes #7164

[yschimke]

@oldergod related to #7297 somewhat, I wonder if we want to allow adding an EventListener to a Call before it's executed or cancelled?

[oldergod]

LGTM but needs a Jesse review before merging

[yschimke]

@swankjesse any thoughts on this?

[yschimke]

@swankjesse ping, it would be good to get this into an alpha for bridge integrations.

[swankjesse]

I’m not sold on this.

I think the top-level goal is reasonable, but this implementation isn’t consistent with our other with methods on interceptors – this collects all events; not the events downstream of proceed. In particular I think the with method would at minimum need to be add.

But then I don’t like other side-effects this can trigger. Like if the interceptor runs 2x, it’ll add the listener 2x.

I think if we really wanted this behavior, we’d be better off adding interceptors to Call objects. And we practically already have that already in OkHttpClient.

Perhaps we start with some use cases and build the API to address them, rather than taking interceptors and trying to make them more powerful.

[yschimke]

Ok, will rework.