return Arrays.stream(DosError.DOS_ERROR_CODES).filter(pair -> pair[0] == dosErrorCode).map(pair -> pair[1]).findFirst();
    }

    @Test
    @DisplayName("DOS_ERROR_CODES is non‑null and non‑empty")
    void testCodesArrayExistence() {
        assertNotNull(DosError.DOS_ERROR_CODES, "DOS_ERROR_CODES should be non‑null");

        assertFalse(thumbnailGenerator.generate(null, tempOutputFile));
    }

    @Test
    public void test_generate_withEmptyThumbnailId() {
        // Test generation with empty thumbnail ID
        assertFalse(thumbnailGenerator.generate("", tempOutputFile));
    }

    @Test
    public void test_generate_withNullOutputFile() {
        // Test generation with null output file

    // occur in practice.
    if (safeMin >= Character.MIN_HIGH_SURROGATE) {
      // The safe range is empty or the all safe code points lie in or above the
      // surrogate range. Either way the character range is empty.
      this.safeMinChar = Character.MAX_VALUE;
      this.safeMaxChar = 0;
    } else {
      // The safe range is non-empty and contains values below the surrogate

   * from the map.
   *
   * The get method returns a WrappedCollection, which decorates the collection
   * in the map (if the key is present) or an empty collection (if the key is
   * not present). When the collection delegate in the WrappedCollection is
   * empty, the multimap may contain subsequently added values for that key. To
   * handle that situation, the WrappedCollection checks whether map contains

        testData.add(createRelatedContent("python", "Python Programming", ""));
        mockBhv.setTestData(testData);

        int count = relatedContentHelper.load();
        assertEquals(1, count); // One virtual host key (empty)

        String[] results = relatedContentHelper.getRelatedContents("java");
        assertEquals(1, results.length);
        assertEquals("Java Programming", results[0]);

        suggester.createIndexIfNothing();

        assertEquals("Empty index should have 0 words", 0, suggester.getAllWordsNum());
    }

    @Test
    public void test_getDocumentWordsNum_onEmptyIndex() throws Exception {
        Suggester suggester = createSuggester();
        suggester.createIndexIfNothing();

        assertEquals("Empty index should have 0 document words", 0, suggester.getDocumentWordsNum());
    }

	// ErrRegistered registered
	ErrRegistered = errors.New("registered")
	// ErrInvalidField invalid field
	ErrInvalidField = errors.New("invalid field")
	// ErrEmptySlice empty slice found
	ErrEmptySlice = errors.New("empty slice found")
	// ErrDryRunModeUnsupported dry run mode unsupported
	ErrDryRunModeUnsupported = errors.New("dry run mode unsupported")
	// ErrInvalidDB invalid db
	ErrInvalidDB = errors.New("invalid db")

		return err
	}
	if (!r.Filter.Tag.IsEmpty() || len(r.Filter.And.Tags) != 0) && !r.DelMarkerExpiration.Empty() {
		return errInvalidRuleDelMarkerExpiration
	}
	if !r.Expiration.set && !r.Transition.set && !r.NoncurrentVersionExpiration.set && !r.NoncurrentVersionTransition.set && r.DelMarkerExpiration.Empty() {
		return errXMLNotWellFormed
	}
	return nil
}

        return new FessUserBean(user);
    }

    /**
     * Gets the cookie remember-me key for persistent login.
     * Currently returns empty as remember-me functionality is not enabled.
     *
     * @return an optional thing containing the remember-me key, or empty if not configured
     */
    @Override
    protected OptionalThing<String> getCookieRememberMeKey() {
        // example to use remember-me

  }

  /**
   * Returns the string if it is not null, or an empty string otherwise.
   *
   * @param string the string to test and possibly return
   * @return {@code string} if it is not null; {@code ""} otherwise
   */
  static String nullToEmpty(@Nullable String string) {
    return (string == null) ? "" : string;
  }

  /**
   * Returns the string if it is not empty, or a null string otherwise.
   *