title: SpringBoot 2.4.0, no log file written (logging.file.name)
body: <p>I tried to use <code>logging.file.name=springboot.log</code> to set my log file, but no log file would written. But it's very confusing that <code>springboot.txt</code> works. This following is my settings in <code>application.properties</code>:</p>
  <pre><code>logging.level.com.demo=trace
  
  # For the following files, I just keep one and comment the others
  logging.file.name=springboot.yml   # Works
  logging.file.name=springboot.xml   # Works
  logging.file.name=springboot.txt   # Works
  logging.file.name=springboot.log   # Does not work
  
  logging.file.name=logging/springboot.yml   # Works
  logging.file.name=logging/springboot.log   # Does not work
  </code></pre>