∀ {α : Type u_1} {β : Type u_2} {mα : MeasurableSpace α} {x : MeasurableSpace β}
  {κ : ProbabilityTheory.Kernel α (β × ℝ)} {ν : ProbabilityTheory.Kernel α β} (f : α × β → StieltjesFunction ℝ),
  ProbabilityTheory.IsCondKernelCDF f κ ν → Measurable fun a => (f a).measure