Function<? super T, ? extends E> elementFunction, ToIntFunction<? super T> countFunction) {
    checkNotNull(elementFunction);
    checkNotNull(countFunction);
    return Collector.of(
        LinkedHashMultiset::create,
        (multiset, t) ->
            multiset.add(checkNotNull(elementFunction.apply(t)), countFunction.applyAsInt(t)),
        (multiset1, multiset2) -> {
          multiset1.addAll(multiset2);

    assertEquals(2, copy.size());
    assertSame(copy, copy.iterator().next().member);
  }

  /*
   * The behavior of toString() and iteration is tested by LinkedHashMultiset,
   * which shares a lot of code with HashMultiset and has deterministic
   * iteration order.
   */

import static junit.framework.TestCase.fail;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.LinkedHashMultiset;
import com.google.common.collect.Multimap;
import com.google.common.collect.Multiset;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;

    }

    {
      ImmutableMultiset.Builder<String> builder = ImmutableMultiset.builder();
      Multiset<@Nullable String> multisetWithNull =
          LinkedHashMultiset.create(Arrays.<@Nullable String>asList("a", null, "b"));
      assertThrows(
          NullPointerException.class, () -> builder.addAll((Multiset<String>) multisetWithNull));
    }
  }

        return HashMultiset.create(contents);
      }
    },
    LinkedHashMultisetImpl {
      @Override
      public <E extends Comparable<E>> Multiset<E> create(Collection<E> contents) {
        return LinkedHashMultiset.create(contents);
      }
    },
    ConcurrentHashMultisetImpl {
      @Override
      public <E extends Comparable<E>> Multiset<E> create(Collection<E> contents) {

    }

    {
      ImmutableMultiset.Builder<String> builder = ImmutableMultiset.builder();
      Multiset<@Nullable String> multisetWithNull =
          LinkedHashMultiset.create(Arrays.<@Nullable String>asList("a", null, "b"));
      assertThrows(
          NullPointerException.class, () -> builder.addAll((Multiset<String>) multisetWithNull));
    }
  }

 *
 * <h3>Implementations</h3>
 *
 * <ul>
 *   <li>{@link ImmutableMultiset}
 *   <li>{@link ImmutableSortedMultiset}
 *   <li>{@link HashMultiset}
 *   <li>{@link LinkedHashMultiset}
 *   <li>{@link TreeMultiset}
 *   <li>{@link EnumMultiset}
 *   <li>{@link ConcurrentHashMultiset}
 * </ul>
 *
 * <p>If your values may be zero, negative, or outside the range of an int, you may wish to use

 *
 * <h3>Implementations</h3>
 *
 * <ul>
 *   <li>{@link ImmutableMultiset}
 *   <li>{@link ImmutableSortedMultiset}
 *   <li>{@link HashMultiset}
 *   <li>{@link LinkedHashMultiset}
 *   <li>{@link TreeMultiset}
 *   <li>{@link EnumMultiset}
 *   <li>{@link ConcurrentHashMultiset}
 * </ul>
 *
 * <p>If your values may be zero, negative, or outside the range of an int, you may wish to use