guava/src/com/google/common/collect/Multimaps.java
@Beta
  @SuppressWarnings("unchecked")
  // safe by specification of ListMultimap.asMap()
  public static <K, V> Map<K, List<V>> asMap(ListMultimap<K, V> multimap) {
    return (Map<K, List<V>>) (Map<K, ?>) multimap.asMap();
  }
@Beta
  @SuppressWarnings("unchecked")
  // safe by specification of ListMultimap.asMap()
  public static <K, V> Map<K, List<V>> asMap(ListMultimap<K, V> multimap) {
    return (Map<K, List<V>>) (Map<K, ?>) multimap.asMap();
  }
Returns {@link ListMultimap#asMap multimap.asMap()}, with its type corrected from {@code Map<K,
Collection<V>>} to {@code Map<K, List<V>>}.

@since 15.0