/**
 * Collectors not present in {@code java.util.stream.Collectors} that are not otherwise associated
 * with a {@code com.google.common} type.
 *
 * @author Louis Wasserman
 * @since 21.0
 */
@GwtCompatible
public final class MoreCollectors {

  /*
   * TODO(lowasser): figure out if we can convert this to a concurrent AtomicReference-based
   * collector without breaking j2cl?
   */

   * collector without breaking j2cl?
   */
  private static final Collector<Object, ?, Optional<Object>> TO_OPTIONAL =
      Collector.of(
          () -> new ToOptionalState<>(null),
          ToOptionalState::add,
          ToOptionalState::combine,
          ToOptionalState::getOptional,
          Collector.Characteristics.UNORDERED);

  /**
   * A collector that converts a stream of zero or one elements to an {@code Optional}.

   * the collection operation is performed. (This differs from the {@code Collector} returned by
   * {@link Collectors#toMap(Function, Function)}, which throws an {@code IllegalStateException}.)
   *
   * @since NEXT
   */
  public static <T extends @Nullable Object, K extends Comparable<? super K>, V>
      Collector<T, ?, ImmutableSortedMap<K, V>> toImmutableSortedMap(
          Function<? super T, ? extends K> keyFunction,

   * {@link Collectors#toMap(Function, Function)}, which throws an {@code IllegalStateException}.)
   *
   * @since NEXT
   */
  @IgnoreJRERequirement // Users will use this only if they're already using streams.
  public static <T extends @Nullable Object, K extends Comparable<? super K>, V>
      Collector<T, ?, ImmutableSortedMap<K, V>> toImmutableSortedMap(

   * from the {@code Collector} returned by {@link Collectors#toMap(Function, Function)}, which
   * throws an {@code IllegalStateException}.)
   *
   * @since 33.2.0 (available since 21.0 in guava-jre)
   */
  @IgnoreJRERequirement // Users will use this only if they're already using streams.
  public static <T extends @Nullable Object, K, V>
      Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(

                    value = stream((String[]) value).get(stream -> stream.collect(Collectors.joining("\n")));
                } else if (value instanceof List) {
                    @SuppressWarnings("unchecked")
                    final List<String> list = (List<String>) value;
                    value = list.stream().collect(Collectors.joining("\n"));
                }
            } else if (dateFieldSet.contains(key)) {

   * IllegalArgumentException} is thrown when the collection operation is performed. (This differs
   * from the {@code Collector} returned by {@link Collectors#toMap(Function, Function)}, which
   * throws an {@code IllegalStateException}.)
   *
   * @since 21.0
   */
  public static <T extends @Nullable Object, K, V>
      Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
          Function<? super T, ? extends K> keyFunction,

                            .distinct()
                            .collect(Collectors.joining("\n")));
                    form.virtualHosts = stream(entity.getVirtualHosts())
                            .get(stream -> stream.filter(StringUtil::isNotBlank).map(String::trim).collect(Collectors.joining("\n")));
                    form.name = null;
                });

        String trimmed = stdout.trim();
        if (trimmed.isEmpty()) {
            return Collections.emptyList();
        }
        return Arrays.stream(trimmed.split("\\s+"))
            .map(String::trim)
            .filter(s -> !s.isEmpty())
            .collect(Collectors.toList());
    }

    private record ExecResult(
        String stdout,
        String stderr,

                            .collect(Collectors.groupingBy(Pair::getFirst, Collectors.mapping(Pair::getSecond, Collectors.toList())));
                    appendJson("search-field", searchFieldMap, buf).append(',');
                    final Map<String, List<String>> requestHeaderMap = entity.getRequestHeaderList()
                            .stream()