@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
public class TreeMultimapExplicitTest extends TestCase {

  /**
   * Compare strings lengths, and if the lengths are equal compare the strings. A {@code null} is
   * less than any non-null value.
   */
  private enum StringLength implements Comparator<@Nullable String> {
    COMPARATOR;

    @Override
    public int compare(@Nullable String first, @Nullable String second) {

@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
public class TreeMultimapExplicitTest extends TestCase {

  /**
   * Compare strings lengths, and if the lengths are equal compare the strings. A {@code null} is
   * less than any non-null value.
   */
  private enum StringLength implements Comparator<@Nullable String> {
    COMPARATOR;

    @Override
    public int compare(@Nullable String first, @Nullable String second) {