Aspect that, when applied to a declaration, reports a warning when any other declaration tries to use it, unless the using declaration
is also marked as experimental.
[AttributeUsage(AttributeTargets.Class|AttributeTargets.Struct|AttributeTargets.Enum|AttributeTargets.Constructor|AttributeTargets.Method|AttributeTargets.Property|AttributeTargets.Field|AttributeTargets.Event|AttributeTargets.Interface|AttributeTargets.Delegate)]
public class ExperimentalAttribute : Attribute, IAspect<IDeclaration>, IAspect, ICompileTimeSerializable, ITemplateProvider, IEligible<IDeclaration>