for (K key : multimap().keySet()) {
      assertTrue(multimap().asMap().get(key) instanceof List);
    }
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testAsMapRemoveImplementsList() {
    List<K> keys = new ArrayList<>(multimap().keySet());
    for (K key : keys) {
      resetCollection();
      assertTrue(multimap().asMap().remove(key) instanceof List);
    }
  }

 * Null row keys, columns keys, and values are not supported.
 *
 * <p>Lookups by row key are often faster than lookups by column key, because the data is stored in
 * a {@code Map<R, Map<C, V>>}. A method call like {@code column(columnKey).get(rowKey)} still runs
 * quickly, since the row key is provided. However, {@code column(columnKey).size()} takes longer,
 * since an iteration across all row keys occurs.
 *

        assertFalse(result.isPresent());
    }

    public void test_ofNullable_withMap() {
        Map<String, Object> testValue = new HashMap<>();
        testValue.put("key1", "value1");
        testValue.put("key2", 42);

        OptionalEntity<Map<String, Object>> result = OptionalUtil.ofNullable(testValue);

        assertNotNull(result);
        assertTrue(result.isPresent());

        RenderDataUtil.register(data, "key1", null);
        assertNull(data.getDataMap().get("key1"));
    }

    public void test_register_string() {
        RenderData data = new RenderData();
        RenderDataUtil.register(data, "key1", "test value");
        assertEquals("test value", data.getDataMap().get("key1"));

        RenderDataUtil.register(data, "key2", "");

    }

    /** Case 5: Overwrite processing for multiple fields, existing overwrite keys are also properly removed */
    public void test_mergeResponseData_multipleOverwrite() {
        Map<String, Object> dataMap = new HashMap<>();
        // Case where the initial dataMap also contains overwrite keys
        dataMap.put("m", "M0");
        dataMap.put("n.overwrite", "N0_old");

 * shared resources.
 *
 * @param <K> the most general type of keys this listener can listen for; for example {@code Object}
 *     if any key is acceptable
 * @param <V> the most general type of values this listener can listen for; for example {@code
 *     Object} if any key is acceptable
 * @author Charles Fry
 * @since 10.0
 */
@GwtCompatible
public interface RemovalListener<K, V> {

   * equal.
   */
  boolean areEqual();

  /**
   * Returns an unmodifiable map containing the entries from the left map whose keys are not present
   * in the right map.
   */
  Map<K, V> entriesOnlyOnLeft();

  /**
   * Returns an unmodifiable map containing the entries from the right map whose keys are not
   * present in the left map.
   */
  Map<K, V> entriesOnlyOnRight();

  /**

        return ImmutableMultiset.copyOf(keys);
      }
    },
    COPY_OF_ITERATOR {
      @Override
      public ImmutableMultiset<Object> create(List<?> keys) {
        return ImmutableMultiset.copyOf(keys.iterator());
      }
    },
    BUILDER_ADD_ENTRY_BY_ENTRY {
      @Override
      public ImmutableMultiset<Object> create(List<?> keys) {

  }

  /**
   * Returns an immutable map whose keys are the distinct elements of this {@code FluentIterable}
   * and whose value for each key was computed by {@code valueFunction}. The map's iteration order
   * is the order of the first appearance of each key in this iterable.
   *
   * <p>When there are multiple instances of a key in this iterable, it is unspecified whether

  }

  /**
   * Returns an immutable map whose keys are the distinct elements of this {@code FluentIterable}
   * and whose value for each key was computed by {@code valueFunction}. The map's iteration order
   * is the order of the first appearance of each key in this iterable.
   *
   * <p>When there are multiple instances of a key in this iterable, it is unspecified whether