[logback-dev] multiple appender-refs in <root> : unexpected behaviour ?

Using logback-classic in Maven:     <dependency>       <groupId>ch.qos.logback</groupId>      <artifactId>logback-classic</artifactId>      <version>1.5.18</version>      <scope>runtime</scope>     </dependency>  If one <root> appender-ref is defined (STDOUT) but another is undefined (CLOUD_LOGGING):   <root level="info">     <appender-ref ref="STDOUT" />    <appender-ref ref="CLOUD_LOGGING" />     </root> logback fails to  set the defined appender in <root>. In main() after server.start()I see WARN in Logger[org.eclipse.jetty.server.Server] - No appenders present in context [default] for logger [org.eclipse.jetty.server.Server]. Is this expected behaviour ? Would be better if it selected whichever is defined.