assertNull(map.get(unmappedKey));
  }

  public void testGetNull() {
    Map<K, V> map = makeEitherMap();
    if (allowsNullKeys) {
      if (allowsNullValues) {
        // TODO: decide what to test here.
      } else {
        assertEquals(map.containsKey(null), map.get(null) != null);
      }
    } else {
      try {
        map.get(null);
      } catch (NullPointerException optional) {
      }
    }

  private static <E extends @Nullable Object> boolean addAllImpl(
      Multiset<E> self, Multiset<? extends E> elements) {
    // It'd be nice if we could specialize for ImmutableMultiset here without also retaining
    // its code when it's not in scope...
    if (elements instanceof AbstractMapBasedMultiset) {
      return addAllImpl(self, (AbstractMapBasedMultiset<? extends E>) elements);

    ImmutableSet<Integer> elements = ImmutableSet.of(1, 2, 3);
    Set<Set<Integer>> powerSet = powerSet(elements);
    // The API doesn't promise this iteration order, but it's convenient here.
    Iterator<Set<Integer>> i = powerSet.iterator();
    assertEquals(ImmutableSet.of(), i.next());
    assertEquals(ImmutableSet.of(1), i.next());
    assertEquals(ImmutableSet.of(2), i.next());

    // contract to guarantee ordering among runnables we'd have to modify the logic here to allow
    // it.
    executeListener(runnable, executor);
  }

  /**
   * Runs this execution list, executing all existing pairs in the order they were added. However,
   * note that listeners added after this point may be executed before those previously added, and

              current);
          int next = current + occurrences;
          if (countMap.replace(element, current, next)) {
            return current;
          }
        }
        // If we're still here, there was a race, so just try again.
      }
    }

    /**
     * Removes a number of occurrences of the specified element from this multiset. If the multiset

            return new Iterator<Integer>() {
              @Override
              public void remove() {
                // We should throw here, but we won't!
              }

              @Override
              public Integer next() {
                // We should throw here, but we won't!
                return 0;
              }

              @Override
              public boolean hasNext() {

import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A class that implements {@code Comparable} without generics, such as those found in libraries
 * that support Java 1.4 and before. Our library needs to do the bare minimum to accommodate such
 * types, though their use may still require an explicit type parameter and/or warning suppression.
 *
 * @author Kevin Bourrillion
 */

      @Override
      public int hashCode() {
        return 1;
      }
    }
  }

  private static void assertContains(String expectedSubstring, String actual) {
    // TODO(kevinb): use a Truth assertion here
    if (!actual.contains(expectedSubstring)) {
      fail("expected <" + actual + "> to contain <" + expectedSubstring + ">");
    }
  }

   *     ranges 0..9, a..z and A..Z are always safe and should not be specified here)
   * @param plusForSpace true if ASCII space should be escaped to {@code +} rather than {@code %20}
   * @throws IllegalArgumentException if any of the parameters were invalid
   */
  public PercentEscaper(String safeChars, boolean plusForSpace) {

 * Tests for AbstractByteHasher.
 *
 * @author Colin Decker
 */
public class AbstractByteHasherTest extends TestCase {

  public void testBytes() {
    TestHasher hasher = new TestHasher(); // byte order insignificant here
    byte[] expected = {1, 2, 3, 4, 5, 6, 7, 8};
    hasher.putByte((byte) 1);
    hasher.putBytes(new byte[] {2, 3, 4, 5, 6});
    hasher.putByte((byte) 7);
    hasher.putBytes(new byte[] {});