sst files not being deleted

[wellington-felix-movile]

Hi everyone! First of all thank you for porting leveldb to Java, awesome work!
I was running some tests and ran into what seems to be a bug, although I'm not sure.
Here is the code I'm using (in kotlin):

fun main() {
    val db = Iq80DBFactory.factory.open(File("storage-test"), Options())

    repeat(100_000) {
        db.put(it.toString().toByteArray(), Random.nextBytes(1000))
        println("Inserted id=$it")
    }
    repeat(100_000) {
        try {
            db.delete(it.toString().toByteArray())
            println("Deleted id=$it")
        } catch (e: Exception) {
            println("[ERROR] error deleting key=$it. ex: $e")
        }
    }
    db.close()
}

Basically I'm just inserting 100K entries with a random byte array payload of size 1KB. Right after the insertion I then delete all entries. What happens is that about 50 .sst files are created but never deleted from disk. Shouldn't the deleteObsoleteFiles() method in DBImpl.java remove these leftover files? Am I missing something here?
Appreciate any help!