title: Intellij: how to convert indents for all files
body: <p>I know how to convert indent for a single file. I go to edit -> convert indent -> space/tab.</p>
  
  <p>But I want to do this for all files under a directory.</p>
  
  <p>I try click on a directory and then go to edit -> convert indent, but the options are grayed out.</p>
  
  <p><a href="https://i.stack.imgur.com/3FrRS.png" rel="noreferrer"><img src="https://i.stack.imgur.com/3FrRS.png" alt="enter image description here"></a></p>