title: Get build requestor using Groovy script (Jenkins / email-ext)
body: <p>I want to get the username and/or email address of the build requestor in a post-build script.</p>
  
  <p><em>Sidenote: I want the requestor so I can set the email sender of the post-build email notification dynamically in the email-ext plugin's pre-send script.</em></p>
  
  <p><a href="http://javadoc.jenkins-ci.org/hudson/model/AbstractBuild.html" rel="nofollow"><code>AbstractBuild</code></a> has built-in support for <code>AbstractBuild.getCulprits()</code> and <code>AbstractBuild.hasParticipant(User user)</code> but I can't find a method for retrieving the requestor. I can't find any useful reference in <a href="http://javadoc.jenkins-ci.org/hudson/model/class-use/User.html" rel="nofollow">reference list</a> to the <code>User</code> class either.</p>