readModsStamp

contentKey -> row for the user shards.

Keyed on contentKey, NOT on the shard name: a jar re-extracted under a fresh temp name every boot (Paper does this for a plugin's bundled jars) is unrecognizable by name and unchanged by content. The last column is the source jar, written for whoever has to read this file, never parsed — last because a file name is the one column free to hold a |. A row without the shard's length and mtime reads as no row, so one written before they were rebuilds its shard once.