/lib/udev/rules.d/51-usb-device.rules is in dolphin-emu 5.0+dfsg-1+b1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 | #GameCube Controller Adapter
SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", ATTRS{idVendor}=="057e", ATTRS{idProduct}=="0337", TAG+="uaccess"
#Mayflash DolphinBar
SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", ATTRS{idVendor}=="057e", ATTRS{idProduct}=="0306", TAG+="uaccess"
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