Rollingfileappender Generates some garbage values in log file

Question

I am using below configuration file to generate logs.

<?xml version="1.0" encoding="UTF-8"?>
<Configuration monitorinterval="30" status="warn" strict="true">
    <Properties>
        <Property name="logFileName">logs/stdlog</Property>
    </Properties>
    <Appenders>
        <Appender type="Console" name="Console" target="SYSTEM_OUT">
            <Layout type="PatternLayout" pattern="%-4level|%d{DEFAULT}|[%t]  />
        </Appender>

        <RollingFile name="rollingLogFile"
            fileName="${logFileName}.txt"
            filePattern="${logFileName}-%d{MM-dd-yyyy}-%i.txt"
            ignoreExceptions="false">
            <PatternLayout>
                <pattern>%-4level|%d{DEFAULT}|[%t] </pattern>
            </PatternLayout>
            <Policies>
                <SizeBasedTriggeringPolicy size="20 MB" />
            </Policies>
            <DefaultRolloverStrategy max="10"/>
        </RollingFile>
    </Appenders>

    <Loggers>
        <Root level="Info">
            <AppenderRef ref="rollingLogFile" />
            <AppenderRef ref="Console" />
        </Root>
    </Loggers>
</Configuration> 

But it generates some garbage values in log file at starting. Below is screenshot. what is wrong here ?