assertThrows(IllegalArgumentException.class, () -> parse("softValues, weakValues"));

    assertThrows(IllegalArgumentException.class, () -> parse("weakValues, softValues"));

    assertThrows(IllegalArgumentException.class, () -> parse("weakValues, weakValues"));
  }

  public void testParse_writeExpirationDays() {
    CacheBuilderSpec spec = parse("expireAfterWrite=10d");

    return ImmutableList.of(createMapMaker().weakKeys(), createMapMaker().weakKeys().weakValues());
  }

  private static Iterable<MapMaker> allWeakValueStrengthMakers() {
    return ImmutableList.of(
        createMapMaker().weakValues(), createMapMaker().weakKeys().weakValues());
  }

  public void testNullParameters() throws Exception {
    NullPointerTester tester = new NullPointerTester();

    return ImmutableList.of(createMapMaker().weakKeys(), createMapMaker().weakKeys().weakValues());
  }

  private static Iterable<MapMaker> allWeakValueStrengthMakers() {
    return ImmutableList.of(
        createMapMaker().weakValues(), createMapMaker().weakKeys().weakValues());
  }

  public void testNullParameters() throws Exception {
    NullPointerTester tester = new NullPointerTester();

 *   <li>{@code weakKeys}: sets {@link CacheBuilder#weakKeys}.
 *   <li>{@code softValues}: sets {@link CacheBuilder#softValues}.
 *   <li>{@code weakValues}: sets {@link CacheBuilder#weakValues}.
 *   <li>{@code recordStats}: sets {@link CacheBuilder#recordStats}.
 * </ul>
 *
 * <p>The set of supported keys will grow as {@code CacheBuilder} evolves, but existing keys will
 * never be removed.

 *   <li>{@code weakKeys}: sets {@link CacheBuilder#weakKeys}.
 *   <li>{@code softValues}: sets {@link CacheBuilder#softValues}.
 *   <li>{@code weakValues}: sets {@link CacheBuilder#weakValues}.
 *   <li>{@code recordStats}: sets {@link CacheBuilder#recordStats}.
 * </ul>
 *
 * <p>The set of supported keys will grow as {@code CacheBuilder} evolves, but existing keys will
 * never be removed.

 * equals} method) to determine equality for keys or values. However, if {@link #weakKeys} was
 * specified, the map uses identity ({@code ==}) comparisons instead for keys. Likewise, if {@link
 * #weakValues} was specified, the map uses identity comparisons for values.
 *
 * <p>The view collections of the returned map have <i>weakly consistent iterators</i>. This means

    assertThrows(IllegalStateException.class, builder1::weakKeys);
  }

  @J2ktIncompatible
  @GwtIncompatible // weakValues
  public void testValueStrengthSetTwice() {
    CacheBuilder<Object, Object> builder1 = CacheBuilder.newBuilder().weakValues();
    assertThrows(IllegalStateException.class, builder1::weakValues);
    assertThrows(IllegalStateException.class, builder1::softValues);

    assertThrows(IllegalStateException.class, builder1::weakKeys);
  }

  @J2ktIncompatible
  @GwtIncompatible // weakValues
  public void testValueStrengthSetTwice() {
    CacheBuilder<Object, Object> builder1 = CacheBuilder.newBuilder().weakValues();
    assertThrows(IllegalStateException.class, builder1::weakValues);
    assertThrows(IllegalStateException.class, builder1::softValues);

            } else {
              return "0";
            }
          }
        };

    LoadingCache<Integer, String> recursiveCache =
        CacheBuilder.newBuilder().weakKeys().weakValues().build(recursiveLoader);
    cacheRef.set(recursiveCache);
    assertThat(recursiveCache.getUnchecked(3)).isEqualTo("3, 2, 1, 0");

    recursiveLoader =
        new CacheLoader<Integer, String>() {

            } else {
              return "0";
            }
          }
        };

    LoadingCache<Integer, String> recursiveCache =
        CacheBuilder.newBuilder().weakKeys().weakValues().build(recursiveLoader);
    cacheRef.set(recursiveCache);
    assertThat(recursiveCache.getUnchecked(3)).isEqualTo("3, 2, 1, 0");

    recursiveLoader =
        new CacheLoader<Integer, String>() {