ExperimentalExtendedContracts
This marker distinguishes the experimental extended contract declaration API and is used to opt-in for that feature when declaring extended contracts of user functions.
Any usage of a declaration annotated with @ExperimentalExtendedContracts
must be accepted either by annotating that usage with the OptIn annotation, e.g. @OptIn(ExperimentalExtendedContracts::class)
, or by using the compiler argument -opt-in=kotlin.contracts.ExperimentalExtendedContracts
.