public static Optional<List<Locale.LanguageRange>> getAcceptableLanguages() {
    return Optional.ofNullable(ACCEPT_LANGUAGE_CONTEXT_KEY.get());
  }
@Test
  void getAcceptableLanguages() {
    when(clientConnectionManager.getAcceptableLanguages(any()))
        .thenReturn(Optional.empty());

    assertTrue(getRequestAttributes().getAcceptableLanguagesList().isEmpty());

    when(clientConnectionManager.getAcceptableLanguages(any()))
        .thenReturn(Optional.of(Locale.LanguageRange.parse("en,ja")));

    assertEquals(List.of("en", "ja"), getRequestAttributes().getAcceptableLanguagesList());
  }