org.yoshiori 以下の DEBUG 以上のものは logging.log に出して、さらに、WARN 以上のものは ALERT にも出したいんだけど、どうやんの？？？

logback.xml

<configuration>
  <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
    <Target>System.out</Target>
    <layout class="ch.qos.logback.classic.PatternLayout">
      <Pattern>%d{HH:mm:ss} [%thread] %-5level %logger{36} - %msg%n
      </Pattern>
    </layout>
  </appender>

  <!--Daily rolling file appender -->
  <appender name="FILE"
    class="ch.qos.logback.core.rolling.RollingFileAppender">
    <File>logging.log</File>
    <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
      <FileNamePattern>logging.%d{yyyy-MM-dd}.log</FileNamePattern>
      <MaxHistory>30</MaxHistory>
    </rollingPolicy>
    <layout class="ch.qos.logback.classic.PatternLayout">
      <Pattern>%-4relative [%thread] %-5level %logger{35} - %msg%n
      </Pattern>
    </layout>
  </appender>

  <!--Daily rolling file appender -->
  <appender name="ALERT"
    class="ch.qos.logback.core.rolling.RollingFileAppender">
    <File>/var/log/alert_log</File>
    <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
      <FileNamePattern>/var/log/alert_log.%d{yyyy-MM-dd}</FileNamePattern>
    </rollingPolicy>
    <layout class="ch.qos.logback.classic.PatternLayout">
      <Pattern>%-4relative [%thread] %-5level %logger{35} - %msg%n
      </Pattern>
    </layout>
    <filter class="ch.qos.logback.classic.filter.ThresholdFilter"><!-- これ -->
      <level>ERROR</level>
    </filter>
  </appender>

  <logger name="org.yoshiori" level="DEBUG">
    <appender-ref ref="FILE" />
    <appender-ref ref="ALERT" />
  </logger>

  <root>
    <level value="INFO" />
    <appender-ref ref="STDOUT" />
    <appender-ref ref="FILE" />
  </root>
</configuration>