*
     * @param key   the key of the feature
     * @param value the value of the feature
     */
    public void addFeature(final String key, final String value) {
        if (StringUtil.isBlank(key) || StringUtil.isBlank(value)) {
            throw new CrawlerSystemException("key or value is null.");
        }

        featureMap.put(key, value);
    }

    /**
     * Adds a property to the extractor.

<?xml version="1.0" encoding="UTF-8"?>
<project name="dbflute" basedir=".">
	<property name="mydbflute.dir" value="${basedir}/mydbflute" />
	<property name="target.dir" value="${basedir}/target" />
	<property name="branch.name" value="fess-15.4" />
	<property name="mydbflute.url" value="https://github.com/lastaflute/lastaflute-example-waterfront/archive/${branch.name}.zip" />

	<target name="mydbflute.check">
		<condition property="mydbflute.exists">

    public boolean containsValue(final Object value) {
        return indexOf(value) >= 0;
    }

    /**
     * Returns the index for the specified value.
     *
     * @param value
     *            the value
     * @return the index for the value, or {@literal -1} if the value is not contained
     */
    public int indexOf(final Object value) {
        if (value != null) {

    /**
     * Trims space characters from the value.
     * @param value The value to trim.
     * @return The trimmed value.
     */
    protected String trimSpace(final String value) {
        if (trimSpaceEnabled) {
            final Matcher matcher = SPACE_PATTERN.matcher(value);
            return matcher.replaceAll(" ").trim();
        }
        return value;
    }

    /**

    @Required
    @Min(value = 1)
    @Max(value = 2147483647)
    @ValidateTypeFailure
    public Integer numOfThread;

    /** The interval time between crawl requests in milliseconds (required, 0 to 2147483647). */
    @Required
    @Min(value = 0)
    @Max(value = 2147483647)
    @ValidateTypeFailure
    public Integer intervalTime;

    /** The boost value for search ranking (required). */

    /**
     * Set the value of hostname, used in parameter comment. <br>
     * Even if empty string, treated as empty plainly. So "IF pmb != null" is false if empty.
     * @param hostname The parameter value of hostname. (NotNull)
     */
    public void setHostname(String hostname) {
        registerVariable("hostname", hostname);
    }

    /**
     * Set the value of jobname, used in parameter comment. <br>

    protected LocalDateTime toLocalDateTime(final Object value) {
        if (value != null) {
            try {
                final Instant instant = Instant.from(DateTimeFormatter.ISO_INSTANT.parse(value.toString()));
                return LocalDateTime.ofInstant(instant, ZoneId.systemDefault());
            } catch (final DateTimeParseException e) {
                logger.debug("Invalid date format: {}", value, e);
            }
        }

        // nothing
    }

    /**
     * Parses parameter string into a map.
     *
     * @param value the parameter string
     * @return the parameter map
     */
    public static Map<String, String> parse(final String value) {
        final Map<String, String> paramMap = new LinkedHashMap<>();
        if (value != null) {
            int unknownKey = 0;

 *            The type of the first value
 * @param <T2>
 *            The type of the second value
 */
public class Pair<T1, T2> {

    /** The first value */
    protected T1 first;

    /** The second value */
    protected T2 second;

    /**
     * Creates and returns a pair of two values.
     *
     * @param <T1>
     *            The type of the first value
     * @param <T2>

    }

    /**
     * Converts a wildcard value to lowercase if configured to do so.
     *
     * @param value The wildcard value to potentially convert
     * @return The value in lowercase if lowercaseWildcard is true, otherwise the original value
     */
    protected String toLowercaseWildcard(final String value) {
        if (lowercaseWildcard) {
            return value.toLowerCase(Locale.ROOT);
        }