title: What do the icons mean next to the column names in IntelliJ?
body: <p><a href="https://i.stack.imgur.com/6okdL.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/6okdL.png" alt="enter image description here"></a></p>
  
  <p>Could somebody explain at least these 3 versions?</p>
  
  <ol>
  <li>yellow column in table</li>
  <li>empty table</li>
  <li>no icon</li>
  </ol>