* create a class that implements {@link Disposable} and register it with this class.
 * </p>
 *
 * @author koichik
 */
public abstract class DisposableUtil {

    /**
     * Do not instantiate.
     */
    protected DisposableUtil() {
    }

    /** Registered {@link Disposable} */
    protected static final Deque<Disposable> disposables = newLinkedList();

    /**

import java.util.Map;

import org.codelibs.core.exception.ClIllegalArgumentException;
import org.codelibs.core.message.MessageFormatter;
import org.codelibs.core.misc.DisposableUtil;

/**
 * Logger interface.
 *
 * @author higa
 */
public class Logger {

    /**
     * Log output levels.
     */
    public enum LogLevel {
        /** Debug */
        DEBUG,