void testJoinSingleNullElement() {
        String result = StringUtil.join(",", (CharSequence) null);
        assertEquals("null", result);
    }

    @Test
    @DisplayName("Should handle whitespace delimiter")
    void testJoinWithWhitespaceDelimiter() {
        String result = StringUtil.join("   ", "spaced", "out");
        assertEquals("spaced   out", result);
    }

    @Test

        assertNull(result, "getAnchorSet should return null for blank string");

        result = crawlerThread.getAnchorSet("   ");
        assertNull(result, "getAnchorSet should return null for whitespace string");
    }

    /**
     * Test getAnchorSet with list of URLs
     */
    @Test
    public void test_getAnchorSet_withList() {
        FessCrawlerThread crawlerThread = new FessCrawlerThread();

            final String[] parts = line.split("=", 2);
            final String key = parts[0];
            // remove optional leading and trailing quotes and whitespace
            final String value = parts[1].replaceAll("^['\"]?\\s*", "").replaceAll("\\s*['\"]?$", "");

            values.put(key, value.toLowerCase());
        });

        return values;
    }

        while (st.hasMoreElements()) {
            list.add(st.nextElement().toString());
        }
        return list.toArray(new String[list.size()]);
    }

    /**
     * Removes whitespace from the left side of the string.
     *
     * @param text
     *            The text to trim
     * @return The resulting string
     */
    public static final String ltrim(final String text) {

      }
    }
  }

  /**
   * Reads the first line from a file. The line does not include line-termination characters, but
   * does include other leading and trailing whitespace.
   *
   * @param file the file to read from
   * @param charset the charset used to decode the input stream; see {@link StandardCharsets} for
   *     helpful predefined constants

    public ExecJob logLevel(final String logLevel) {
        this.logLevel = logLevel;
        return this;
    }

    /**
     * Sets the log suffix for this job execution.
     * The suffix is trimmed and whitespace is replaced with underscores.
     *
     * @param logSuffix the suffix to append to log file names
     * @return this ExecJob instance for method chaining
     */

        item.setNewInput(newSpecialInput);
        assertEquals(newSpecialInput, item.toLineString());
    }

    @Test
    public void test_whitespaceHandling() {
        // Test with various whitespace scenarios
        ProtwordsItem item1 = new ProtwordsItem(1, "  word  ");
        assertEquals("  word  ", item1.getInput());
        assertEquals("  word  ", item1.toLineString());

        assertEquals(emptyMessage, exception.getMessage());
        assertNull(exception.getCause());
    }

    @Test
    public void test_getMessage_withWhitespaceMessage() {
        // Test constructor with whitespace-only message
        String whitespaceMessage = "   ";
        SsoProcessException exception = new SsoProcessException(whitespaceMessage);

        assertEquals(whitespaceMessage, exception.getMessage());

import static com.google.common.base.CharMatcher.is;
import static com.google.common.base.CharMatcher.isNot;
import static com.google.common.base.CharMatcher.noneOf;
import static com.google.common.base.CharMatcher.whitespace;
import static com.google.common.truth.Truth.assertThat;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;

                "- rephrase or rewrite correct lines just to improve the style.",
                "- add or remove line breaks, unless the original English content changed.",
                "- change formatting or whitespace unless absolutely required.",
                "Only change what must be changed. The goal is to minimize diffs for easier human review.",