LineTable
Which method owns a source line, read from the class file's LineNumberTable — the descriptor a StackTraceElement does not carry, and the only thing that separates same-named obf overloads.
Only spigot gets here (every other namespace answers owner-free), and there the jar's table is the live one: ByteBuddy advice leaves the target method's lines untouched, and Mixin offsets merged code into a range ABOVE the target's instead of renumbering it — added methods included, a line table being per-method to begin with. A line that matches nothing yields null, so an unknown rewriter costs the obf name we already showed.