filtered.put("a", 1);
    filtered.put("b", 2);
    assertEquals(ImmutableMap.of("a", 1, "b", 2), filtered);

    assertThrows(
        IllegalArgumentException.class,
        () -> filtered.putAll(ImmutableMap.of("c", 3, "zzz", 4, "b", 5)));

    assertEquals(ImmutableMap.of("a", 1, "b", 2), filtered);
  }

  public void testFilteredKeysFilteredReflectsBackingChanges() {

    public @Nullable V put(K key, V value) {
      assertTrue(Thread.holdsLock(mutex));
      return super.put(key, value);
    }

    @Override
    public void putAll(Map<? extends K, ? extends V> map) {
      assertTrue(Thread.holdsLock(mutex));
      super.putAll(map);
    }

    @Override
    public Set<K> keySet() {
      assertTrue(Thread.holdsLock(mutex));
      return super.keySet();
    }

   * {@code put()} or {@code putAll()}, or {@code setValue()} on its entries.
   *
   * <p>In contrast, the maps returned by {@code rowMap().get()} have the same behavior as those
   * returned by {@link #row}. Those maps may support {@code setValue()}, {@code put()}, and {@code
   * putAll()}.
   *
   * @return a map view from each row key to a secondary map from column keys to values

   *     FIRST_LETTER_MULTIMAP.putAll('b', Arrays.asList('a', 'n', 'a', 'n', 'a'));
   *     FIRST_LETTER_MULTIMAP.putAll('a', Arrays.asList('p', 'p', 'l', 'e'));
   *     FIRST_LETTER_MULTIMAP.putAll('c', Arrays.asList('a', 'r', 'r', 'o', 't'));
   *     FIRST_LETTER_MULTIMAP.putAll('a', Arrays.asList('s', 'p', 'a', 'r', 'a', 'g', 'u', 's'));
   *     FIRST_LETTER_MULTIMAP.putAll('c', Arrays.asList('h', 'e', 'r', 'r', 'y'));
   * }

   *     FIRST_LETTER_MULTIMAP.putAll('b', Arrays.asList('a', 'n', 'a', 'n', 'a'));
   *     FIRST_LETTER_MULTIMAP.putAll('a', Arrays.asList('p', 'p', 'l', 'e'));
   *     FIRST_LETTER_MULTIMAP.putAll('c', Arrays.asList('a', 'r', 'r', 'o', 't'));
   *     FIRST_LETTER_MULTIMAP.putAll('a', Arrays.asList('s', 'p', 'a', 'r', 'a', 'g', 'u', 's'));
   *     FIRST_LETTER_MULTIMAP.putAll('c', Arrays.asList('h', 'e', 'r', 'r', 'y'));
   * }

  }

  // Null support depends on the underlying table and function.
  @J2ktIncompatible
  @GwtIncompatible // NullPointerTester
  @Override
  public void testNullPointerInstance() {}

  // put() and putAll() aren't supported.
  @Override
  public void testPut() {
    assertThrows(UnsupportedOperationException.class, () -> table.put("foo", 1, 'a'));
    assertSize(0);
  }

  @Override

   * copied table may have different iteration orders. For more control over the ordering, create a
   * {@link Builder} and call {@link Builder#orderRowsBy}, {@link Builder#orderColumnsBy}, and
   * {@link Builder#putAll}
   *
   * <p>Despite the method name, this method attempts to avoid actually copying the data when it is
   * safe to do so. The exact circumstances under which a copy will or will not be performed are

      return put(entry.getKey(), entry.getValue());
    }

    @CanIgnoreReturnValue
    public Builder<K, V> putAll(Map<? extends K, ? extends V> map) {
      return putAll(map.entrySet());
    }

    @CanIgnoreReturnValue
    public Builder<K, V> putAll(Iterable<? extends Entry<? extends K, ? extends V>> entries) {
      for (Entry<? extends K, ? extends V> entry : entries) {
        put(entry);

      super.put(entry);
      return this;
    }

    @CanIgnoreReturnValue
    @Override
    public Builder<K, V> putAll(Map<? extends K, ? extends V> map) {
      return putAll(map.entrySet());
    }

    @CanIgnoreReturnValue
    @Override
    public Builder<K, V> putAll(Iterable<? extends Entry<? extends K, ? extends V>> entries) {
      for (Entry<? extends K, ? extends V> entry : entries) {
        put(entry);

        } else if (targetLocations == null) {
            locations = sourceLocations;
        } else {
            locations = new LinkedHashMap<>();
            locations.putAll(sourceDominant ? targetLocations : sourceLocations);
            locations.putAll(sourceDominant ? sourceLocations : targetLocations);
        }

        return new InputLocation(-1, -1, InputSource.merge(source.getSource(), target.getSource()), locations);