val classifierNames = directives[Directives.RESOLVE_EXTENSION_CLASSIFIER].toSet()
            val callableNames = directives[Directives.RESOLVE_EXTENSION_CALLABLE].toSet()
            check(classifierNames.isNotEmpty() || callableNames.isNotEmpty()) {
                "Extension file $name does not specify any RESOLVE_EXTENSION_CLASSIFIER or RESOLVE_EXTENSION_CALLABLE"
            }