LOGBACK: No context given for c.q.l.core.rolling.SizeAndTimeBasedRollingPolicy

when I try to use spring boot default configuration to configure a rolling log files,logback show tips like title,so I view source(v2.2.6.RELEASE) to find the reason. in 150 lines of DefaultLogbackConfiguration.java,

private void setRollingPolicy(RollingFileAppender<ILoggingEvent> appender, LogbackConfigurator config,
			String logFile) {
		SizeAndTimeBasedRollingPolicy<ILoggingEvent> rollingPolicy = new SizeAndTimeBasedRollingPolicy<>();
		...
		rollingPolicy.setTotalSizeCap(new FileSize(totalSizeCap.toBytes()));
		appender.setRollingPolicy(rollingPolicy);
		...
	}

when then rollingPolicy setRollingPolicy,logback show this tips,the tips info in 74 line of ContextAwareBase.java,the problem is not serious but very vexed, please repair it as soon as possible,thanks!