return appendFileterPath(buf, escape(s));
    }

    /**
     * Escapes special regex characters in a string to create a literal pattern.
     * Handles anchor characters (^ and $) specially to preserve their regex meaning.
     *
     * @param s the string to escape
     * @return an escaped regex pattern, or empty string for comments
     */
    protected String escape(final String s) {

      .assertLogMatch(Regex("""User-Agent: okhttp/.+"""))
      .assertLogEqual("--> END GET")
      .assertLogMatch(Regex("""<-- 200 OK $url \(\d+ms\)"""))
      .assertLogEqual("Content-Type: text/html; charset=0")
      .assertLogMatch(Regex("""Content-Length: \d+"""))
      .assertLogMatch(Regex(""))
      .assertLogEqual("Body with unknown charset")
      .assertLogMatch(Regex("""<-- END HTTP \(\d+ms, 25-byte body\)"""))

      .assertLogMatch(Regex("""callStart: Request\{method=POST, url=$url\}"""))
      .assertLogMatch(Regex("""proxySelectStart: $url"""))
      .assertLogMatch(Regex("""proxySelectEnd: \[DIRECT]"""))
      .assertLogMatch(Regex("""dnsStart: ${url.host}"""))
      .assertLogMatch(Regex("""dnsEnd: \[.+]"""))
      .assertLogMatch(Regex("""connectStart: ${url.host}/.+ DIRECT"""))
      .assertLogMatch(Regex("""connectEnd: http/1.1"""))

    /**
     * Adds custom system properties that match the given regex pattern to the command list.
     *
     * @param cmdList the command list to add properties to
     * @param regex the regular expression pattern to match property names
     */
    protected void addFessCustomSystemProperties(final List<String> cmdList, final String regex) {
        if (StringUtil.isNotBlank(regex)) {
            final Pattern pattern = Pattern.compile(regex);

            false, false, "keyword", 0, 0, null, null, false, null, null, null, null, null, false);
    protected final ColumnInfo _columnRegex = cci("regex", "regex", null, null, String.class, "regex", null, false, false, false, "keyword",
            0, 0, null, null, false, null, null, null, null, null, false);

     * @param regex the regular expression to use for splitting the string
     * @return a stream of substrings resulting from splitting the input string, or an empty stream if the input is {@code null}
     */
    public static StreamOf<String> split(final String value, final String regex) {
        return stream(value == null ? null : value.split(regex));
    }

    /**

            if (entity.getTerm().startsWith(regexPrefix)) {
                final String regex = entity.getTerm().substring(regexPrefix.length());
                if (StringUtil.isBlank(regex)) {
                    logger.warn("Unknown regex pattern: {}", entity.getTerm());
                } else {
                    pair.getSecond().add(new Pair<>(Pattern.compile(regex), entity.getContent()));
                }
            } else {

        assertEquals(0, results.length);
    }

    public void test_load_invalidRegex() {
        List<RelatedContent> testData = new ArrayList<>();
        testData.add(createRelatedContent("regex:", "Invalid Regex", ""));
        mockBhv.setTestData(testData);

        // Should not throw exception, just log warning
        relatedContentHelper.load();

  }

  @GwtIncompatible // java.util.regex.Pattern
  public void testPatternSplitWordBoundary_singleCharInput() {
    String string = "f";
    Iterable<String> words = Splitter.on(Pattern.compile("\\b")).split(string);
    assertThat(words).containsExactly("f").inOrder();
  }

  @AndroidIncompatible // Apparently Gingerbread's regex API is buggy.
  @J2ktIncompatible // Kotlin Native's regex is based on Apache Harmony, like old Android

import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Collectors;

import org.apache.commons.lang3.time.DurationFormatUtils;
import org.apache.commons.text.StringEscapeUtils;
import org.apache.logging.log4j.LogManager;