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

    for (MultimapBuilderWithKeys<?> builderWithKeys :
        ImmutableList.of(
            MultimapBuilder.hashKeys(),
            MultimapBuilder.linkedHashKeys(),
            MultimapBuilder.treeKeys(),
            MultimapBuilder.enumKeys(RoundingMode.class))) {
      for (MultimapBuilder<?, ?> builder :
          ImmutableList.of(
              builderWithKeys.arrayListValues(),

  /**
   * Creates a new, empty {@code HashMultimap} with the default initial capacities.
   *
   * <p>You may also consider the equivalent {@code
   * MultimapBuilder.hashKeys().hashSetValues().build()}, which provides more control over the
   * underlying data structure.
   */
  public static <K extends @Nullable Object, V extends @Nullable Object>
      HashMultimap<K, V> create() {

    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;

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;

   *                  str -> str.charAt(0),
   *                  str -> str.substring(1),
   *                  MultimapBuilder.treeKeys().arrayListValues()::build));
   *
   * // is equivalent to
   *
   * static final ListMultimap<Character, String> FIRST_LETTER_MULTIMAP;
   *
   * static {
   *     FIRST_LETTER_MULTIMAP = MultimapBuilder.treeKeys().arrayListValues().build();
   *     FIRST_LETTER_MULTIMAP.put('b', "anana");