Cannot specify `userId` on track events

[apuig]

Is your feature request related to a problem? Please describe.
I would like to specify the userId without relaying on userInfo state.

In a test, using the java compatibility:

analytics.identify("user1", JsonObject with traits);
analytics.track("activity1", JsonObject with properties);

sometimes it generates a track event without userId, but regardless of this, I want to be able to send a track without a previous identify.

Describe the solution you'd like
Some signature to send a track event with the desired userId.

Describe alternatives you've considered
After checking Events.kt, looks like its not possible to customize this attribute.

[apuig]

sorry, just realized its a duplicated issue
#112
#173
#233

workarround does it, but will be nice to avoid these gymnastics

[wenxi-zeng]

hi @apuig. glad you found a workaround. besides what you mentioned, we have identified a few optimization needed for the SDK used in server use cases. they are in our roadmap but we just haven't had chance to get to them because other priorities. will get back to you once we have them ready. thanks!