plugins/maven-plugin/run-headless.html

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  <p>
  If a build doesn't require access to desktop (only using command line tools and tests) this option can be checked.
  <p>
  This option allows Jenkins to configure the build process in headless mode 
  by adding <code>-Djava.awt.headless=true</code> to <code>MAVEN_OPTS</code>. 
  This is usefull on OSX to avoid Dock icons taking focus. This option may also in future releases be used to select adequate agent instance.
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