*/
  public static <T extends @Nullable Object> Iterator<T> concat(
      Iterator<? extends Iterator<? extends T>> inputs) {
    return new ConcatenatedIterator<>(inputs);
  }

  /** Concats a varargs array of iterators without making a defensive copy of the array. */
  static <T extends @Nullable Object> Iterator<T> concatNoDefensiveCopy(
      Iterator<? extends T>... inputs) {

    assertThat(readFileOrNull(getDirtyFile("k1", 0))).isNull()
  }

  private fun assertJournalEquals(vararg expectedBodyLines: String) {
    assertThat(readJournalLines()).isEqualTo(
      listOf(DiskLruCache.MAGIC, DiskLruCache.VERSION_1, "100", "2", "") + expectedBodyLines,
    )
  }

  private fun createJournal(vararg bodyLines: String) {
    createJournalWithHeader(
      DiskLruCache.MAGIC,