Java Unit types missing mult(U) functions

[bhall-ctre]

It looks like all the Java unit types have per(U) functions, but many of them are missing generic mult(U) functions. For now, users can use MultUnit.combine(a, b), but it would be nice if users could directly do something like Volts.per(Rotation.mult(Second)) for all units (as I believe was the case with 2024 units).

[SamCarlberg]

So, a caveat to this is type erasure (of course) with combinatory units and their subclasses. Something like this wouldn't be possible:

public class Per<N extends Unit, D extends Unit> extends Unit {
  N mult(D denom) { ... }

  <Other extends Unit> MultUnit<? extends Per<N, D>, Other> mult(Other other) { ... }
}

Because N and Other both erase down to Unit and result in identical method signatures

But basic non-combinatory types like voltage and angle should be fine. My main concern would be lack of consistency, like having only some units support mult while others don't or only in a limited way.

[bhall-ctre]

Given that mult() and per() are both used moreso to create new units rather than to perform dimensional analysis (which is more what I would expect from times() and divide()), I think that's a fair trade-off. MultUnit.combine(a, b) already doesn't do any dimensional analysis either.