I am using logstash-logback-encoder to print logs in json format.

My logback.xml looks like below:-

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
        <encoder class="net.logstash.logback.encoder.LogstashEncoder">
            <includeContext>false</includeContext>
            <fieldNames>
                <timestamp>timestamp</timestamp>
                <version>[ignore]</version>
                <levelValue>[ignore]</levelValue>
            </fieldNames>
        </encoder>
    </appender>
    <appender name="stash"
        class="ch.qos.logback.core.rolling.RollingFileAppender">        
        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <fileNamePattern>/tmp/SolrUpdater.%d{yyyy-MM-dd}.log
            </fileNamePattern>
            <maxHistory>7</maxHistory>
        </rollingPolicy>
        <encoder class="net.logstash.logback.encoder.LogstashEncoder">
            <includeContext>false</includeContext>
            <fieldNames>
                <timestamp>timestamp</timestamp>
                <version>[ignore]</version>
                <levelValue>[ignore]</levelValue>
            </fieldNames>
        </encoder>
    </appender>
    <root level="error">
        <appender-ref ref="CONSOLE" />
        <appender-ref ref="stash" />
    </root>
</configuration>

Can someone let me know how can I display all level in lowercase like error, rather than the default ERROR and WARN as warning?

Thanks,

Debraj