*
     * @return the application type string, or empty string if not set
     */
    public static String getAppType() {
        final String appType = System.getenv(FESS_APP_TYPE);
        if (StringUtil.isNotBlank(appType)) {
            return appType;
        }
        return StringUtil.EMPTY;
    }

    /**

   * ordering of the values for each key.
   *
   * <p>A non-empty {@link SetMultimap} cannot be equal to a non-empty {@link ListMultimap}, since
   * their {@link #asMap} views contain unequal collections as values. However, any two empty
   * multimaps are equal, because they both have empty {@link #asMap} views.
   */
  @Override
  boolean equals(@Nullable Object obj);

  /**

     *
     * @return default upgrade options
     */
    public static UpgradeOptions createDefaultOptions() {
        UpgradeOptions options = mock(UpgradeOptions.class);
        when(options.all()).thenReturn(Optional.empty());
        when(options.infer()).thenReturn(Optional.empty());
        when(options.model()).thenReturn(Optional.empty());

    expectContents();
  }

  // retainAll(null)

  /*
   * AbstractCollection fails the retainAll(null) test when the subject
   * collection is empty, but we'd still like to test retainAll(null) when we
   * can. We split the test into empty and non-empty cases. This allows us to
   * suppress only the former.
   */

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)

     *
     * @param id the unique identifier of the data configuration
     * @return an OptionalEntity containing the DataConfig if found, empty otherwise
     * @throws IllegalArgumentException if id is null or empty
     */
    public OptionalEntity<DataConfig> getDataConfig(final String id) {
        return dataConfigBhv.selectByPK(id);
    }

    /**

        assertEquals("Malformed kerberos ticket", exception.getMessage(), "The exception message should indicate a malformed ticket.");
    }

    /**
     * Test constructor with an empty token.
     * Empty token causes readObject() to return null, which leads to NullPointerException.
     */
    @Test
    void testConstructor_EmptyToken() {
        // 1. GIVEN
        byte[] emptyToken = new byte[0];

  }

  public void testEmptiesFirst() {
    Optional<String> empty = Optional.empty();
    Optional<String> abc = Optional.of("abc");
    Optional<String> z = Optional.of("z");

    Comparator<Optional<String>> comparator = emptiesFirst(comparing(String::length));
    testComparator(comparator, empty, z, abc);

    // Just demonstrate that no explicit type parameter is required

     * @param dataMap additional data map (not currently used)
     * @return the normalized title, or empty string if title is null
     */
    public String getTitle(final ResponseData responseData, final String title, final Map<String, Object> dataMap) {
        if (title == null) {
            return StringUtil.EMPTY; // empty
        }

        final int[] spaceChars = getSpaceChars();

  public void testConcat() {
    assertThat(Chars.concat()).isEqualTo(EMPTY);
    assertThat(Chars.concat(EMPTY)).isEqualTo(EMPTY);
    assertThat(Chars.concat(EMPTY, EMPTY, EMPTY)).isEqualTo(EMPTY);
    assertThat(Chars.concat(ARRAY1)).isEqualTo(ARRAY1);
    assertThat(Chars.concat(ARRAY1)).isNotSameInstanceAs(ARRAY1);
    assertThat(Chars.concat(EMPTY, ARRAY1, EMPTY)).isEqualTo(ARRAY1);
    assertThat(Chars.concat(ARRAY1, ARRAY1, ARRAY1))

   * otherwise returns an empty stream.
   */
  public static <T> Stream<T> stream(com.google.common.base.Optional<T> optional) {
    return optional.isPresent() ? Stream.of(optional.get()) : Stream.empty();
  }

  /**
   * If a value is present in {@code optional}, returns a stream containing only that element,
   * otherwise returns an empty stream.
   *