*
   * {@snippet :
   * for (B b0 : sets.get(0)) {
   *   for (B b1 : sets.get(1)) {
   *     ...
   *     ImmutableList<B> tuple = ImmutableList.of(b0, b1, ...);
   *     // operate on tuple
   *   }
   * }
   * }
   *
   * <p>Note that if any input set is empty, the Cartesian product will also be empty. If no sets at

import java.util.Objects;
import java.util.PriorityQueue;
import java.util.Queue;
import org.jspecify.annotations.NonNull;
import org.jspecify.annotations.Nullable;

/**
 * This class contains static utility methods that operate on or return objects of type {@link
 * Iterator}. Except as noted, each method has a corresponding {@link Iterable}-based method in the
 * {@link Iterables} class.
 *

      DiskLruCache(filesystem, cacheDir, appVersion, 2, Int.MAX_VALUE.toLong(), taskRunner).also {
        toClose.add(it)
      }
    assertFailsWith<IOException> {
      cache["k1"]
    }

    // Now let it operate normally.
    filesystem.setFaultyDelete(cacheDir / "k1.0.tmp", false)
    filesystem.setFaultyDelete(cacheDir, false)
    val snapshot = cache["k1"]
    assertThat(snapshot).isNull()
  }

  @ParameterizedTest