@Target(allowedTargets = {AnnotationTarget.CLASS, AnnotationTarget.ANNOTATION_CLASS, AnnotationTarget.PROPERTY, AnnotationTarget.FIELD, AnnotationTarget.LOCAL_VARIABLE, AnnotationTarget.VALUE_PARAMETER, AnnotationTarget.CONSTRUCTOR, AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY_GETTER, AnnotationTarget.PROPERTY_SETTER, AnnotationTarget.TYPEALIAS}) 
public @interface ExperimentalApi

This annotation marks the API that is considered experimental. The behavior of such API may be changed or the API may be removed completely in any further release.

Any usage of a declaration annotated with @ExperimentalStdlibApi must be accepted either by annotating that usage with the OptIn annotation, e.g. @OptIn(ExperimentalStdlibApi::class), or by using the compiler argument -Xopt-in=kotlin.ExperimentalStdlibApi.

Annotation ExperimentalApi