/usr/lib/ubuntu-ui-toolkit/examples/unit-converter/unit-converter.desktop is in ubuntu-ui-toolkit-examples 0.1.46+14.04.20140408.1-0ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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Name=converter
Comment=My project description
Exec=/usr/bin/qmlscene $@ /usr/lib/ubuntu-ui-toolkit/examples/unit-converter/unit-converter.qml
Icon=qmlscene
Terminal=false
Type=Application
X-Ubuntu-Touch=true
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