There is no documentation that says zero isn't okay, and the closed interval
[0, k] described by the documentation is perfectly well-defined even when k is
zero. As far as I can tell, there is no reason *not* to support zero: a random
variable that always returns the same value is still a random variable.
absl::Uniform will happily generate on the interval [0, 1) for the same
reason.
PiperOrigin-RevId: 694649518
Change-Id: Ib940406f762a30e27c19c846c45bd908ae8411c3
