return resp;
        });

        // For Trans2FindNext2 calls
        final int[] nextCall = { 0 };
        when(tree.send(any(Trans2FindNext2.class), any(Trans2FindFirst2Response.class))).thenAnswer((InvocationOnMock inv) -> {
            Trans2FindFirst2Response resp = inv.getArgument(1);
            int call = nextCall[0]++;
            String[] names = batches.get(call + 1);

    return object : MutableIterator<String> {
      private val delegate: MutableIterator<DiskLruCache.Snapshot> = cache.snapshots()
      private var nextUrl: String? = null
      private var canRemove = false

      override fun hasNext(): Boolean {
        if (nextUrl != null) return true

        canRemove = false // Prevent delegate.remove() on the wrong item!
        while (delegate.hasNext()) {
          try {