title: Delete all files in directory (but not directory) - one liner solution
body: <p>I want to delete all files inside ABC directory.</p>
  
  <p>When I tried with <code>FileUtils.deleteDirectory(new File("C:/test/ABC/"));</code> it also deletes folder ABC.</p>
  
  <p>Is there a one liner solution where I can delete files inside directory but not directory?</p>