*       that the {@linkplain ListMultimap#get collection of values} associated with a given key
 *       fulfills the {@link java.util.List} contract.
 *   <dt>{@link SetMultimap}
 *   <dd>An extension of {@link Multimap} which has order-independent equality and does not allow
 *       duplicate entries; that is, while a key may appear twice in a {@code SetMultimap}, each

    checkNotNull(executor, "Executor was null.");
    try {
      executor.execute(listener);
    } catch (Exception e) { // sneaky checked exception
      // ListenableFuture's contract is that it will not throw unchecked exceptions, so log the bad
      // runnable and/or executor and swallow it.
      log.get()
          .log(
              Level.SEVERE,

    class BA implements B, A {}
    AB ab = new AB();
    BA ba = new BA();
    new EqualsTester()
        .addEqualityGroup(newDelegatingList(LIST1))
        // Actually, this violates List#equals contract.
        // But whatever, no one is going to proxy List (hopefully).
        .addEqualityGroup(newDelegatingList(LIST1))
        .addEqualityGroup(newDelegatingList(LIST2))
        .addEqualityGroup(

 * natural ordering of the elements, if there is no comparator) to test element equality. As a
 * result, if the comparator is not consistent with equals, some of the standard implementations may
 * violate the {@code Set} contract.
 *
 * <p>The {@code standard} methods and the collection views they return are not guaranteed to be
 * thread-safe, even when all of the methods that they depend on are thread-safe.
 *
 * @author Mike Bostock

 *
 * <p><b>Warning:</b> The comparison must be <i>consistent with equals</i> as explained by the
 * {@link Comparable} class specification. Otherwise, the resulting multiset will violate the {@link
 * Collection} contract, which is specified in terms of {@link Object#equals}.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset">{@code Multiset}</a>.
 *

      // assumes that each set is a singleton or less (as is done for the samples)
      for (Object elem : elements) {
        @SuppressWarnings("unchecked") // safe by generator contract
        Entry<String, Collection<Integer>> entry = (Entry<String, Collection<Integer>>) elem;
        Integer value = Iterables.getOnlyElement(entry.getValue());
        builder.put(entry.getKey(), value);
      }

import java.util.Set;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Tests representing the contract of {@link Map}. Concrete subclasses of this base class test
 * conformance of concrete {@link Map} subclasses to that contract.
 *
 * @param <K> the type of keys used by the maps under test
 * @param <V> the type of mapped values used the maps under test
 * @author George van den Driessche

      return Iterators.unmodifiableIterator(iterable.iterator());
    }

    @Override
    public String toString() {
      return iterable.toString();
    }
    // no equals and hashCode; it would break the contract!
  }

  /** Returns the number of elements in {@code iterable}. */
  public static int size(Iterable<?> iterable) {
    return (iterable instanceof Collection)
        ? ((Collection<?>) iterable).size()

          // Checking subtype between declared and actual type bounds
          // adds recursive isSubtypeOf() call and feels complicated.
          // There is no contract one way or another as long as isSubtypeOf() works as expected.
          combined.addAll(asList(typeParam.getBounds()));
          if (combined.size() > 1) { // Object is implicit and only useful if it's the only bound.

 *
 * <p><b>Warning:</b> The comparison must be <i>consistent with equals</i> as explained by the
 * {@link Comparable} class specification. Otherwise, the resulting multiset will violate the {@link
 * java.util.Collection} contract, which is specified in terms of {@link Object#equals}.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset">{@code Multiset}</a>.
 *