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 {
            delegate.next().use { snapshot ->
              val metadata = snapshot.getSource(ENTRY_METADATA).buffer()