title: Import text from file to *.properties
body: <p>I have a file that contains key (<code>public.key.pub</code>):</p>
  
  <pre><code>-----BEGIN PUBLIC KEY----- 
     .....keykeykey....
  -----END PUBLIC KEY-----
  </code></pre>
  
  <p>And I have <code>my-props.properties</code> file:</p>
  
  <pre><code>key1 = value1
  public.key = ${file:public.key.pub}
  </code></pre>
  
  <p>But I can't import key to properties file. How to do this? What syntax?</p>