title: both File.isFile() and File.isDirectory() is returning false
body: <p>I have a file with name  "aaaäaa.xls"</p>
  
  <p>For this, <code>File.isFile()</code> and <code>File.isDirectory()</code> is returning <code>false</code>? why it is returning <code>false</code> in <code>Linux</code>?</p>