*
 * {@snippet :
 * ListMultimap<UserId, ErrorResponse> errorsByUser =
 *     MultimapBuilder.linkedHashKeys().arrayListValues().build();
 * SortedSetMultimap<String, Method> methodsForName =
 *     MultimapBuilder.treeKeys().treeSetValues(this::compareMethods).build();
 * }
 *
 * <p>{@code MultimapBuilder} instances are immutable. Invoking a configuration method has no effect

 *
 * {@snippet :
 * ListMultimap<UserId, ErrorResponse> errorsByUser =
 *     MultimapBuilder.linkedHashKeys().arrayListValues().build();
 * SortedSetMultimap<String, Method> methodsForName =
 *     MultimapBuilder.treeKeys().treeSetValues(this::compareMethods).build();
 * }
 *
 * <p>{@code MultimapBuilder} instances are immutable. Invoking a configuration method has no effect

    return collectingAndThen(
        flatteningToMultimap(
            input -> checkNotNull(keyFunction.apply(input)),
            input -> valuesFunction.apply(input).peek(Preconditions::checkNotNull),
            MultimapBuilder.linkedHashKeys().arrayListValues()::<K, V>build),
        ImmutableListMultimap::copyOf);
  }

  static <T extends @Nullable Object, K, V>
      Collector<T, ?, ImmutableSetMultimap<K, V>> toImmutableSetMultimap(

    return collectingAndThen(
        flatteningToMultimap(
            input -> checkNotNull(keyFunction.apply(input)),
            input -> valuesFunction.apply(input).peek(Preconditions::checkNotNull),
            MultimapBuilder.linkedHashKeys().arrayListValues()::<K, V>build),
        ImmutableListMultimap::copyOf);
  }

  static <T extends @Nullable Object, K, V>
      Collector<T, ?, ImmutableSetMultimap<K, V>> toImmutableSetMultimap(

import com.google.common.collect.ImmutableSet;
import com.google.common.collect.ImmutableSetMultimap;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.common.collect.MultimapBuilder;
import com.google.common.collect.Multimaps;
import com.google.common.collect.Multiset;
import com.google.common.collect.Ordering;
import com.google.common.collect.SetMultimap;

 *   <li>{@link ImmutableSetMultimap}
 *   <li>Configure your own mutable multimap with {@link MultimapBuilder}
 *   <li>{@link LinkedListMultimap} (for one unusual kind of mutable {@code Multimap})
 * </ul>
 *
 * Guava contains a number of other multimap implementations, such as {@link ArrayListMultimap}. In
 * new code, we recommend using {@link MultimapBuilder} instead: It provides better control of how
 * keys and values are stored.
 *