Log file with date not generated

Question

Trying to generate a log file with date.

Below is my xml configuration for log4j. From below configuration its generated only app.log but I am expecting app.log.2020-3-1.

Can someone please help me what is the issue in my configuration?

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/" debug="false">

    <appender name="consoleAppender" class="org.apache.log4j.ConsoleAppender">
        <param name="Target" value="System.out" />
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n" />
        </layout>
    </appender>

    <appender name="file" class="org.apache.log4j.DailyRollingFileAppender">
        <param name="Threshold" value="DEBUG" />
        <param name="append" value="true" />

        <param name="File" value="logs/app.log" />
        <param name="DatePattern" value="'.'yyyy-MM-dd" />

        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n" />
        </layout>
    </appender>   


    <root>
        <priority value="DEBUG"/>
        <appender-ref ref="consoleAppender" />
        <appender-ref ref="file" />
    </root>

</log4j:configuration>