io.ktor.util.java.nio.file.Path -

combineSafe	`fun Path.combineSafe(relativePath: Path): File` Append a relativePath safely that means that adding any extra `..` path elements will not let access anything out of the reference directory (unless you have symbolic or hard links or multiple mount points)
extension	`val Path.extension: String` Finds an extension of the given Path
normalizeAndRelativize	`fun Path.normalizeAndRelativize(): Path` Remove all redundant `.` and `..` path elements. Leading `..` are also considered redundant.