UFile (package = )
    UClass (name = DefaultParameterValuesKt)
        UAnnotationMethod (name = foo)
            UParameter (name = a)
                UAnnotation (fqName = org.jetbrains.annotations.NotNull)
                ULiteralExpression (value = 1)
            UParameter (name = foo)
                UAnnotation (fqName = org.jetbrains.annotations.Nullable)
                ULiteralExpression (value = null)
            UBlockExpression
