title: Adding source files to Gradle project
body: <p>Let's assume I've got a simple Android project which I'm gonna build by Gradle. </p>
  
  <p>Is it possible to <strong>add</strong> sources from arbitrary directory? </p>
  
  <p>So I'd like to keep main sourceSets intact, just to add some java-files which are located in <em>path to sources</em>. </p>