title: Extend properties file by including another properties file. Maven
body: <p>Can I use 'include' option (or something like this) to include any properties file to another properties file?</p>
  
  <p>So,I have two properties files:
  1. "firstPropertiesFile" which contains the next string:</p>
  
  <p>include = secondPropertiesFile       #it's path to second property file</p>
  
  <p>and</p>
  
  <p>"secondPropertiesFile" which contains the next string:</p>
  
  <p>key = value</p>
  
  <p>Also I have resource file (file which will be filtered by resources:resources goal) contains:</p>
  
  <p>${key}</p>
  
  <p>When I invoke resources:resources goal, I expect the next steps:</p>
  
  <ol>
  <li><p>Resources plugin look into firstPropertiesFile file and see that it contains refer to another properties file.</p></li>
  <li><p>The plugin go to reference (path to second property file) and see necessary key and gets value (in our case- value).</p></li>
  </ol>
  
  <p>But this way doesn't work in maven. Could you hint me how to realize this?</p>
  
  <p>P.S. This option is supported in Apache Commons Configuration: <a href="http://commons.apache.org/proper/commons-configuration/userguide/howto_properties.html" rel="noreferrer">http://commons.apache.org/proper/commons-configuration/userguide/howto_properties.html</a>
  ("Includes" chapter).</p>