title: I'm developing an Intellij plugin, can I add a preview of a variable?
body: <p>I am developing an Intellij plugin.</p>
  <p>What I want to do is if there is content defined in the key:value format in file A, when the key is written as text in file B, its value (taken from file A) can be previewed in the editor.</p>
  <p>Just like the image below where you can preview the contents of application.property.</p>
  <p>Does anyone know how?</p>
  <p><a href="https://i.stack.imgur.com/XvnBb.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/XvnBb.png" alt="enter image description here" /></a></p>