title: What is the integrity property inside yarn.lock file?
body: <p>For some reason, the command <code>yarn</code> is modifying the file <code>yarn.lock</code> with a new property to every dependency: <code>integrity</code>.</p>
  
  <p>Git diff:</p>
  
  <blockquote>
    <p>+integrity sha1-zgBCgEX7t9AxwWp7+DV4nxU2arI=</p>
  </blockquote>
  
  <p>I couldn't find documentation about it so my question is - What is it?</p>