How about this...

ExtFormatter.java

/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2009, Red Hat Inc., and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.jboss.logmanager;

import java.util.logging.Formatter;
import java.util.logging.LogRecord;

/**
 * A formatter which handles {@link org.jboss.logmanager.ExtLogRecord ExtLogRecord} instances.
 */
public abstract class ExtFormatter extends Formatter {

    /** {@inheritDoc} */
    public final String format(final LogRecord record) {
        return format(ExtLogRecord.wrap(record));
    }

    /**
     * Format a message using an extended log record.
     *
     * @param extLogRecord the log record
     * @return the formatted message
     */
    public abstract String format(final ExtLogRecord extLogRecord);

    @Override
    public final String formatMessage(final LogRecord record) {
        return format(record);
    }
}