// they have been left as independent tests for clarity.

    if (part.length() < 1 || part.length() > MAX_DOMAIN_PART_LENGTH) {
      return false;
    }

    /*
     * GWT claims to support java.lang.Character's char-classification methods, but it actually only
     * works for ASCII. So for now, assume any non-ASCII characters are valid. The only place this
     * seems to be documented is here:

import com.google.errorprone.annotations.concurrent.GuardedBy;
import com.google.j2objc.annotations.J2ObjCIncompatible;
import com.google.j2objc.annotations.WeakOuter;
import java.lang.ref.WeakReference;
import java.time.Duration;
import java.util.ArrayList;
import java.util.EnumSet;
import java.util.IdentityHashMap;
import java.util.List;
import java.util.Map.Entry;

    /**
     * <p>Unescapes any Java literals found in the <code>String</code> to a
     * <code>Writer</code>.</p> This is a slightly modified version of the
     * StringEscapeUtils.unescapeJava() function in commons-lang that doesn't
     * drop escaped separators (i.e '\,').
     *
     * @param str  the <code>String</code> to unescape, may be null
     * @return the processed string

    /**
     * <p>Unescapes any Java literals found in the <code>String</code> to a
     * <code>Writer</code>.</p> This is a slightly modified version of the
     * StringEscapeUtils.unescapeJava() function in commons-lang that doesn't
     * drop escaped separators (i.e '\,').
     *
     * @param str  the <code>String</code> to unescape, may be null
     * @return the processed string

**Parameters**:
- `q` - Query string
- `num` - Results per page (default: 20)
- `start` - Starting offset (default: 0)
- `fields.label` - Label filter
- `lang` - Language preference

**Example**:
```bash
# Using the recommended endpoint
curl "http://localhost:8080/api/v1/documents?q=search&num=10"

# Or using the legacy endpoint

import java.util.Map;
import java.util.stream.Collectors;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.codelibs.core.beans.util.BeanUtil;
import org.codelibs.core.lang.StringUtil;
import org.codelibs.fess.Constants;
import org.codelibs.fess.app.pager.SearchLogPager;
import org.codelibs.fess.exception.FessSystemException;
import org.codelibs.fess.helper.SystemHelper;

import static com.google.common.collect.CollectPreconditions.checkNonnegative;
import static com.google.common.collect.Iterators.emptyIterator;
import static com.google.common.collect.Maps.immutableEntry;
import static java.lang.Math.max;
import static java.util.Arrays.asList;
import static java.util.Objects.requireNonNull;

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

import java.util.HashMap;
import java.util.Map;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.codelibs.core.io.InputStreamUtil;
import org.codelibs.core.lang.ThreadUtil;
import org.codelibs.fess.crawler.container.StandardCrawlerContainer;
import org.codelibs.fess.crawler.entity.ResponseData;
import org.codelibs.fess.crawler.exception.ChildUrlsException;

import java.util.function.Consumer;

import org.codelibs.core.beans.BeanDesc;
import org.codelibs.core.beans.PropertyDesc;
import org.codelibs.core.beans.factory.BeanDescFactory;
import org.codelibs.core.lang.ClassUtil;

/**
 * Utility for copying properties between JavaBeans or between JavaBeans and {@link Map}.
 * <p>
 * By specifying the source and destination JavaBeans, properties can be copied.
 * </p>
 *
 * <pre>

import javax.xml.xpath.XPathException;
import javax.xml.xpath.XPathNodes;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.codelibs.core.io.InputStreamUtil;
import org.codelibs.core.lang.StringUtil;
import org.codelibs.core.misc.Pair;
import org.codelibs.fess.crawler.Constants;
import org.codelibs.fess.crawler.builder.RequestDataBuilder;
import org.codelibs.fess.crawler.container.CrawlerContainer;