Geoserver homebrew automatic launch OS X 10.10

Question

I have installed Geoserver with homebrew on OS X 10.10. I can not find any launchagent file. So I tried to make my own and put it in ~/Users/myuser/Library/LaunchAgents.

I called this homebrew.mxcl.geoserver.plist

Here is the content. It does not work. Any Ideas? I now have to start Geoserver with

geoserver /path/to/geoserver_data_dir/data

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  <key>KeepAlive</key>
  <true/>
  <key>Label</key>
  <string>homebrew.mxcl.geoserver</string>
  <key>ProgramArguments</key>
  <array>
    <string>geoserver</string>
    <string>/Library/WebServer/geoserver_data_dir/data</string>
  </array>
  <key>RunAtLoad</key>
  <true/>
  <key>WorkingDirectory</key>
  <string>/usr/local/var</string>
</dict>
</plist>