I have changes my config file like below

<configuration debug="true">

    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">

            <Target>System.out</Target>

            <encoder>

               <pattern>%d{yyyy-MM-dd HH:mm:ss} [%thread] %-5level %logger{36} - %msg%n</pattern>

            </encoder>

    </appender>

    <root level="DEBUG">

        <appender-ref ref="STDOUT" />

    </root>

</configuration>

Removed log4j from path. I am also attaching mvn dependency:tree

But still log config file coming as null

10:51:42,695 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Found resource [/home/ubuntu/build-target/restapilayer/restapilayer.logback.xml] at [file:/home/ubuntu/build-target/restapilayer/restapilayer.logback.xml]
10:51:42,860 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - About to instantiate appender of type [ch.qos.logback.core.ConsoleAppender]
10:51:42,863 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - Naming appender as [STDOUT]
10:51:42,869 |-INFO in ch.qos.logback.core.joran.action.NestedComplexPropertyIA - Assuming default type [ch.qos.logback.classic.encoder.PatternLayoutEncoder] for [encoder] property
10:51:42,894 |-INFO in ch.qos.logback.classic.joran.action.RootLoggerAction - Setting level of ROOT logger to DEBUG
10:51:42,895 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [STDOUT] to Logger[ROOT]
10:51:42,895 |-INFO in ch.qos.logback.classic.joran.action.ConfigurationAction - End of configuration.
10:51:42,896 |-INFO in ch.qos.logback.classic.joran.JoranConfigurator@3fd7a715 - Registering current configuration as safe fallback point
2018-01-13 10:51:42 [main] INFO  com.vnera.common.utils.CommonUtils - adding uncaught exception handler hook...
INFO [2018-01-13 10:51:44] o.e.j.u.log:[?:?:?] - [main] - Logging initialized @1792ms    

INFO [2018-01-12 16:25:34] c.v.r.c.v.r.VneraBackendService:[?:?:?] - [main] - Logback used _null_ as the configuration file_