public static final String HC4_CLIENT = "hc4";

    /** Value for HC5 client selection. */
    public static final String HC5_CLIENT = "hc5";

    /** The HC4 HTTP client instance. */
    protected CrawlerClient hc4Client;

    /** The HC5 HTTP client instance. */
    protected CrawlerClient hc5Client;

    /** Flag indicating which client is selected (true = hc5, false = hc4). */
    private boolean useHc5 = true;

    /**

        if (value == null) {
            return new Hc5Authentication[0];
        }

        // If already HC5 Hc5Authentication[], return directly
        if (value instanceof Hc5Authentication[]) {
            return (Hc5Authentication[]) value;
        }

        // If common POJO config, convert to HC5
        if (value instanceof WebAuthenticationConfig[]) {

import org.apache.hc.client5.http.auth.AuthScheme;
import org.apache.hc.client5.http.auth.AuthScope;
import org.apache.hc.client5.http.auth.Credentials;

/**
 * Authentication class for Apache HttpComponents 5.x (HC5).
 * This class provides methods to handle authentication details such as
 * authentication scope, credentials, and authentication scheme.
 *
 * <p>
 * It includes constructors to initialize these details and getter and setter

 */
package org.codelibs.fess.crawler.client.http.config;

import java.util.Date;

/**
 * POJO configuration for HTTP cookies that can be converted to
 * either HC4 Cookie or HC5 Cookie.
 *
 * <p>This class provides a library-independent way to configure
 * cookies that work with both Apache HttpComponents 4.x
 * and 5.x clients.</p>
 *
 * <p>Example usage:</p>
 * <pre>{@code

<components namespace="fessCrawler">
	<include path="crawler/container.xml" />
	<include path="crawler/robotstxt.xml" />
	<include path="crawler/contentlength.xml" />
	<include path="crawler/mimetype.xml" />

	<!-- HC5 (Default) -->
	<component name="internalHttpClient" class="org.codelibs.fess.crawler.client.http.Hc5HttpClient"
		instance="prototype">
		<property name="connectionTimeout">15000</property>

 * governing permissions and limitations under the License.
 */
package org.codelibs.fess.crawler.client.http.config;

/**
 * POJO configuration for credentials that can be converted to
 * either HC4 Credentials or HC5 Credentials.
 *
 * <p>This class provides a library-independent way to configure
 * authentication credentials that work with both Apache HttpComponents 4.x
 * and 5.x clients.</p>
 *
 * <p>Example usage:</p>

/**
 * HcHttpClient is the abstract base class for HTTP client implementations
 * using Apache HttpComponents. This class provides common constants and
 * configurations shared between HC4 and HC5 implementations.
 *
 * <p>Key properties and configurations:</p>
 * <ul>
 *   <li>CONNECTION_TIMEOUT_PROPERTY: Connection timeout setting.</li>
 *   <li>SO_TIMEOUT_PROPERTY: Socket timeout setting.</li>

 */
package org.codelibs.fess.crawler.client.http.config;

import java.util.Map;

/**
 * POJO configuration for web authentication that can be converted to
 * either HC4 Hc4Authentication or HC5 Hc5Authentication.
 *
 * <p>This class provides a library-independent way to configure
 * HTTP authentication that works with both Apache HttpComponents 4.x
 * and 5.x clients.</p>
 *

    └── Hc4HttpClient (fallback) - Apache HttpComponents 4.x

HcHttpClient (abstract base class)
    ├── Hc4HttpClient
    └── Hc5HttpClient
```

Switch via system property: `-Dfess.crawler.http.client=hc4` or `hc5` (default)

**Key Properties**: `connectionTimeout`, `soTimeout`, `proxyHost`, `proxyPort`, `userAgent`, `robotsTxtEnabled`, `ignoreSslCertificate`, `maxTotalConnection`, `defaultMaxConnectionPerRoute`

### CrawlerClientFactory