ifEmpty

@JvmName(name = "ifEmpty_mono_mono")
fun <In : Out, Out> IMonoStep<In>.ifEmpty(alternative: () -> IMonoStep<Out>): IMonoStep<Out>
@JvmName(name = "ifEmpty_flux_mono")
fun <In : Out, Out> IFluxStep<In>.ifEmpty(alternative: () -> IMonoStep<Out>): IFluxStep<Out>