阿里Druid数据源，程序启动或日志记录报错 load filter error, filter not found : logback ，但不影响程序的运行

Druid支持配置多种Filter，配置信息保存在druid-xxx.jar!/META-INF/druid-filter.properties下面，具体如下：

druid.filters.default=com.alibaba.druid.filter.stat.StatFilter
    druid.filters.stat=com.alibaba.druid.filter.stat.StatFilter
    druid.filters.mergeStat=com.alibaba.druid.filter.stat.MergeStatFilter
    druid.filters.counter=com.alibaba.druid.filter.stat.StatFilter
    druid.filters.encoding=com.alibaba.druid.filter.encoding.EncodingConvertFilter
    druid.filters.log4j=com.alibaba.druid.filter.logging.Log4jFilter
    druid.filters.slf4j=com.alibaba.druid.filter.logging.Slf4jLogFilter
    druid.filters.commonlogging=com.alibaba.druid.filter.logging.CommonsLogFilter
    druid.filters.commonLogging=com.alibaba.druid.filter.logging.CommonsLogFilter
    druid.filters.wall=com.alibaba.druid.wall.WallFilter
    druid.filters.config=com.alibaba.druid.filter.config.ConfigFilter

众所周知，logback是slf4j的实现类，按照规定格式，改成下面

spring:
  datasource:
    filters: stat,wall,slf4j