@Override
  protected Map<String, Integer> makePopulatedMap() {
    Table<Character, String, Integer> table = HashBasedTable.create();
    table.put('a', "one", 1);
    table.put('a', "two", 2);
    table.put('a', "three", 3);
    table.put('b', "four", 4);
    return unmodifiableTable(table).row('a');
  }

  }

  @Override
  protected Map<String, Integer> makePopulatedMap() {
    Table<String, Character, Integer> table = HashBasedTable.create();
    table.put("one", 'a', 1);
    table.put("two", 'a', 2);
    table.put("three", 'a', 3);
    table.put("four", 'b', 4);
    return transformValues(table, DIVIDE_BY_2).column('a');
  }

  protected SortedMap<String, Integer> makeEmptyMap() {
    return ImmutableSortedMap.of();
  }

  @Override
  protected SortedMap<String, Integer> makePopulatedMap() {
    return ImmutableSortedMap.of("one", 1, "two", 2, "three", 3);
  }

  @Override
  protected String getKeyNotInPopulatedMap() {
    return "minus one";
  }

  @Override
  protected Integer getValueNotInPopulatedMap() {
    return -1;
  }

  protected Map<String, Integer> makeEmptyMap() {
    throw new UnsupportedOperationException();
  }

  @Override
  Table<String, Character, Integer> makeTable() {
    return ArrayTable.create(asList("one", "two", "three", "four"), asList('a', 'b', 'c'));
  }

    throw new UnsupportedOperationException();
  }

  @Override
  protected Table<Character, String, Integer> makeTable() {
    return ArrayTable.create(asList('a', 'b', 'c'), asList("one", "two", "three", "four"));
  }

 * whose edges have associated non-unique values.
 *
 * <p>A graph is composed of a set of nodes and a set of edges connecting pairs of nodes.
 *
 * <p>There are three primary interfaces provided to represent graphs. In order of increasing
 * complexity they are: {@link Graph}, {@link ValueGraph}, and {@link Network}. You should generally

     * difference is that calling it with <Foo> won't work when an input Future has a @Nullable
     * type. So why even make that error possible by giving callers the choice?
     *
     * On the other hand, the current signature is consistent with the similar allAsList method. And
     * eventually this method may go away entirely in favor of an API like

@GwtCompatible
public enum CollectionSize implements Feature<Collection>, Comparable<CollectionSize> {
  /** Test an empty collection. */
  ZERO(0),
  /** Test a one-element collection. */
  ONE(1),
  /** Test a three-element collection. */
  SEVERAL(3),
  /*
   * TODO: add VERY_LARGE, noting that we currently assume that the fourth
   * sample element is not in any collection
   */

  ANY(ZERO, ONE, SEVERAL);

   * and not contents.
   *
   * <p>This is useful for implementing {@link Object#hashCode()}. For example, in an object that
   * has three properties, {@code x}, {@code y}, and {@code z}, one could write:
   *
   * {@snippet :
   * public int hashCode() {
   *   return Objects.hashCode(getX(), getY(), getZ());
   * }
   * }
   *

@GwtCompatible
public enum CollectionSize implements Feature<Collection>, Comparable<CollectionSize> {
  /** Test an empty collection. */
  ZERO(0),
  /** Test a one-element collection. */
  ONE(1),
  /** Test a three-element collection. */
  SEVERAL(3),
  /*
   * TODO: add VERY_LARGE, noting that we currently assume that the fourth
   * sample element is not in any collection
   */

  ANY(ZERO, ONE, SEVERAL);