* predicate. The returned multimap is a live view of {@code unfiltered}; changes to one affect
   * the other.
   *
   * <p>The resulting multimap's views have iterators that don't support {@code remove()}, but all
   * other methods are supported by the multimap and its views. When adding a key that doesn't

 *           }
 *         });
 * }</pre>
 *
 * <p>The returned cache implements all optional operations of the {@link LoadingCache} and {@link
 * Cache} interfaces. The {@code asMap} view (and its collection views) have <i>weakly consistent
 * iterators</i>. This means that they are safe for concurrent use, but if other threads modify the
 * cache after the iterator is created, it is undefined which of these changes, if any, are

import java.util.SortedMap;
import java.util.SortedSet;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Synchronized collection views. The returned synchronized collection views are serializable if the
 * backing collection and the mutex are serializable.
 *
 * <p>If {@code null} is passed as the {@code mutex} parameter to any of this class's top-level

   * navigable set is accomplished through the returned navigable set (or its views).
   *
   * <p>It is imperative that the user manually synchronize on the returned sorted set when
   * iterating over it or any of its {@code descendingSet}, {@code subSet}, {@code headSet}, or
   * {@code tailSet} views.
   *
   * <pre>{@code
   * NavigableSet<E> set = synchronizedNavigableSet(new TreeSet<E>());

        Iterator<Integer> source = Iterators.forArray(1, 2, 3, 4, 5, 6, 7);
        return Iterators.partition(source, 3);
      }
    }.test();
  }

  public void testPartition_view() {
    List<Integer> list = asList(1, 2);
    Iterator<List<Integer>> partitions = Iterators.partition(list.iterator(), 1);

    // Changes before the partition is retrieved are reflected
    list.set(0, 3);

    TreeSet<Integer> mod = Sets.newTreeSet();
    mod.add(1);
    mod.add(2);
    mod.add(3);

    NavigableSet<Integer> unmod = unmodifiableNavigableSet(mod);

    /* Unmodifiable is a view. */
    mod.add(4);
    assertTrue(unmod.contains(4));
    assertTrue(unmod.descendingSet().contains(4));

    ensureNotDirectlyModifiable(unmod);
    ensureNotDirectlyModifiable(unmod.descendingSet());

    assertSame(refreshKey, map.get(refreshKey));

    // let computation complete
    letGetFinishSignal.countDown();
    getFinishedSignal.await();
    checkNothingLogged();

    // asMap view should have been updated
    assertEquals(2, cache.size());
    assertEquals(getKey + suffix, map.get(getKey));
    assertEquals(refreshKey + suffix, map.get(refreshKey));
  }

    /* No aliasing on inverse operations. */
    assertSame(unmod.inverse(), unmod.inverse());
    assertSame(unmod, unmod.inverse().inverse());

    /* Unmodifiable is a view. */
    mod.put(4, "four");
    assertEquals(true, unmod.get(4).equals("four"));
    assertEquals(true, unmod.inverse().get("four").equals(4));

    /* UnsupportedOperationException on direct modifications. */

    /* No aliasing on inverse operations. */
    assertSame(unmod.inverse(), unmod.inverse());
    assertSame(unmod, unmod.inverse().inverse());

    /* Unmodifiable is a view. */
    mod.put(4, "four");
    assertEquals(true, unmod.get(4).equals("four"));
    assertEquals(true, unmod.inverse().get("four").equals(4));

    /* UnsupportedOperationException on direct modifications. */

    assertSame(refreshKey, map.get(refreshKey));

    // let computation complete
    letGetFinishSignal.countDown();
    getFinishedSignal.await();
    checkNothingLogged();

    // asMap view should have been updated
    assertEquals(2, cache.size());
    assertEquals(getKey + suffix, map.get(getKey));
    assertEquals(refreshKey + suffix, map.get(refreshKey));
  }