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"""))

                                                 data-validation="custom"
                                                 data-validation-regexp="(\+|\-)?\d+(\.\d+)?((e|E)(\+|\-)?\d+)?"
                                                 data-validation-help="number (Float)"/>
                                    </div>
                                </div>

    /**
     * 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);

        regQ(wildcardQuery);
        return wildcardQuery;
    }

    protected RegexpQueryBuilder regRegexpQ(String name, String regexp) {
        checkEsInvalidQuery(name, regexp);
        RegexpQueryBuilder regexpQuery = QueryBuilders.regexpQuery(name, regexp);
        regQ(regexpQuery);
        return regexpQuery;
    }

    protected CommonTermsQueryBuilder regCommonTermsQ(String name, Object text) {

        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;