* load on the garbage collector by only using a constant number of internal objects.
 *
 * <p>This class should not be assumed to be universally superior to {@code
 * java.util.LinkedHashMap}. Generally speaking, this class reduces object allocation and memory
 * consumption at the price of moderately increased constant factors of CPU. Only use this class

 * elements, including {@code null}, are permitted.
 *
 * <p>{@code contains(x)}, {@code add(x)} and {@code remove(x)}, are all (expected and amortized)
 * constant time operations. Expected in the hashtable sense (depends on the hash function doing a
 * good job of distributing the elements to the buckets to a distribution not far from uniform), and

   */
  public static <E> Builder<E> builder() {
    return new Builder<>();
  }

  /**
   * A builder for creating immutable multiset instances, especially {@code public static final}
   * multisets ("constant multisets"). Example:
   *
   * <pre>{@code
   * public static final ImmutableMultiset<Bean> BEANS =
   *     new ImmutableMultiset.Builder<Bean>()
   *         .addCopies(Bean.COCOA, 4)

  public static <K, V> Builder<K, V> builder() {
    return new Builder<>();
  }

  /**
   * A builder for creating immutable {@code SetMultimap} instances, especially {@code public static
   * final} multimaps ("constant multimaps"). Example:
   *
   * <pre>{@code
   * static final Multimap<String, Integer> STRING_TO_INTEGER_MULTIMAP =
   *     new ImmutableSetMultimap.Builder<String, Integer>()
   *         .put("one", 1)

    return new ImmutableList.Builder<>(expectedSize);
  }

  /**
   * A builder for creating immutable list instances, especially {@code public static final} lists
   * ("constant lists"). Example:
   *
   * <pre>{@code
   * public static final ImmutableList<Color> GOOGLE_COLORS
   *     = new ImmutableList.Builder<Color>()
   *         .addAll(WEBSAFE_COLORS)

    return new Builder<>(Ordering.natural());
  }

  /**
   * A builder for creating immutable sorted set instances, especially {@code public static final}
   * sets ("constant sets"), with a given comparator. Example:
   *
   * <pre>{@code
   * public static final ImmutableSortedSet<Number> LUCKY_NUMBERS =
   *     new ImmutableSortedSet.Builder<Number>(ODDS_FIRST_COMPARATOR)

        /*
         * lowasser, 2015-Feb-12: Benchmarks suggest that changing this to UnsignedLongs.remainder
         * and increasing the threshold to 2^32 doesn't pay for itself, and adding another enum
         * constant hurts performance further -- I suspect because bimorphic implementation is a
         * sweet spot for the JVM.
         */
        return (a * b) % m;
      }

      @Override

    return new Builder<>(Ordering.<K>natural().reverse());
  }

  /**
   * A builder for creating immutable sorted map instances, especially {@code public static final}
   * maps ("constant maps"). Example:
   *
   * <pre>{@code
   * static final ImmutableSortedMap<Integer, String> INT_TO_WORD =
   *     new ImmutableSortedMap.Builder<Integer, String>(Ordering.natural())
   *         .put(1, "one")

    try {
      Maps.toMap((Iterable<String>) strings, Functions.constant("foo"));
      fail();
    } catch (NullPointerException expected) {
    }
  }

  public void testToMapWithNullValues() {
    Iterable<String> strings = ImmutableList.of("one", "two", "three");
    try {
      Maps.toMap(strings, Functions.constant(null));
      fail();
    } catch (NullPointerException expected) {
    }
  }

    try {
      Maps.toMap((Iterable<String>) strings, Functions.constant("foo"));
      fail();
    } catch (NullPointerException expected) {
    }
  }

  public void testToMapWithNullValues() {
    Iterable<String> strings = ImmutableList.of("one", "two", "three");
    try {
      Maps.toMap(strings, Functions.constant(null));
      fail();
    } catch (NullPointerException expected) {
    }
  }