title: How does Maven decide what version of a plugin to use, when you don't specify any?
body: <p>I recognized that Maven not always uses the latest version of a plugin.</p>
  
  <p>For example <code>org.codehaus.mojo:sonar-maven-plugin</code> version 2.7 has beed released on 19th of October but on 23th of October, 2.6 was still used by Maven (<code>mvn sonar:sonar</code>).</p>
  
  <p>I even remember some plugins, where the latest version was several minor releases above the version that Maven decided to use.</p>
  
  <p>Is there any (central) index/list/database where Maven looks up what version to use? If yes, where can it be accessed manually?</p>