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);
    }
  }

    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);
    }
  }

   * key. When a key-value pair is added to a multimap that didn't previously
   * contain any values for that key, a new collection generated by
   * createCollection is added to the map. That same collection instance
   * remains in the map as long as the multimap has any values for the key. If
   * all values for the key are removed, the key and collection are removed
   * from the map.
   *

        viewHelper.setUseSession(true);
        assertTrue(viewHelper.isUseSession());

        viewHelper.addInitFacetParam("key1", "value1");
        assertEquals("key1", viewHelper.getInitFacetParamMap().get("value1"));

        viewHelper.addInitGeoParam("key2", "value2");
        assertEquals("key2", viewHelper.getInitGeoParamMap().get("value2"));

        FacetQueryView facetQueryView = new FacetQueryView();

           * We assign these to variables before calling checkNotNull to work around a bug in our
           * nullness checker.
           */
          K key = keyFunction.apply(t);
          V newValue = valueFunction.apply(t);
          accum.put(
              checkNotNull(key, "Null key for input %s", t),
              checkNotNull(newValue, "Null value for input %s", t));
        },
        EnumMapAccumulator::combine,

           * We assign these to variables before calling checkNotNull to work around a bug in our
           * nullness checker.
           */
          K key = keyFunction.apply(t);
          V newValue = valueFunction.apply(t);
          accum.put(
              checkNotNull(key, "Null key for input %s", t),
              checkNotNull(newValue, "Null value for input %s", t));
        },
        EnumMapAccumulator::combine,

  }

  private long runAddSingleThread(int reps) {
    Random random = new Random();
    int nKeys = keys.size();
    long blah = 0;
    for (int i = 0; i < reps; i++) {
      Integer key = keys.get(random.nextInt(nKeys));
      int delta = random.nextInt(5);
      blah += delta;
      multiset.add(key, delta);
    }
    return blah;
  }

  private long runAddRemoveSingleThread(int reps) {

  @Override
  public boolean containsKey(@Nullable Object key) {
    if (unfiltered.containsKey(key)) {
      @SuppressWarnings("unchecked") // k is equal to a K, if not one itself
      K k = (K) key;
      return keyPredicate.apply(k);
    }
    return false;
  }

  @Override
  public Collection<V> removeAll(@Nullable Object key) {
    return containsKey(key) ? unfiltered.removeAll(key) : unmodifiableEmptyCollection();
  }

  @Override
  public boolean containsKey(@Nullable Object key) {
    if (unfiltered.containsKey(key)) {
      @SuppressWarnings("unchecked") // k is equal to a K, if not one itself
      K k = (K) key;
      return keyPredicate.apply(k);
    }
    return false;
  }

  @Override
  public Collection<V> removeAll(@Nullable Object key) {
    return containsKey(key) ? unfiltered.removeAll(key) : unmodifiableEmptyCollection();
  }

 * 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.
 *