c# log4net how to get the file name

Question

I am using the RollingFileAppender to add the date to log file. At the end of a process, I want to email the log file. How can I get the file name that was dynamically created using netcore3.1?

I have seen this answer from 2014, Get log4net log file in C#. The .OfType no longer works.

  <logger name="user_log" additivity="false">
    <level value="Info" />
    <appender-ref ref="user_log" />
  </logger>
  <appender name="user_log" type="log4net.Appender.RollingFileAppender">
    <file value="c:\\logs\\csp\\process_csp_" />
    <datePattern value="yyyy-MM-dd'.log'"/>
    <staticLogFileName value="false" />
    <appendToFile value="true" />
    <layout type="log4net.Layout.PatternLayout">
      <conversionpattern value="%date{yyyy-MM-dd HH:mm:ss} %-5level %message %newline" />
    </layout>
    <lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
  </appender>