assertThat(response1.body.string()).isEqualTo("ABC")
    val cacheEntry =
      fileSystem.allPaths.stream()
        .filter { e: Path -> e.name.endsWith(".0") }
        .findFirst()
        .orElseThrow { NoSuchElementException() }
    corruptCertificate(cacheEntry)
    val response2 = client.newCall(request).execute() // Not Cached!
    assertThat(response2.body.string()).isEqualTo("DEF")
    assertThat(cache.requestCount()).isEqualTo(2)

    public K firstKey() {
      // correctly throws NoSuchElementException when filtered map is empty.
      return keySet().iterator().next();
    }

    @Override
    @ParametricNullness
    public K lastKey() {
      SortedMap<K, V> headMap = sortedMap();
      while (true) {
        // correctly throws NoSuchElementException when filtered map is empty.
        K key = headMap.lastKey();

    public K firstKey() {
      // correctly throws NoSuchElementException when filtered map is empty.
      return keySet().iterator().next();
    }

    @Override
    @ParametricNullness
    public K lastKey() {
      SortedMap<K, V> headMap = sortedMap();
      while (true) {
        // correctly throws NoSuchElementException when filtered map is empty.
        K key = headMap.lastKey();

import java.util.AbstractMap;
import java.util.AbstractQueue;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ConcurrentMap;