/usr/share/gimp/2.0/gradients/Coffee.ggr is in gimp-data 2.8.16-1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | GIMP Gradient
Name: Coffee
1
0.000000 0.949917 1.000000 0.560606 0.435893 0.311332 0.000000 0.300000 0.233262 0.166605 1.000000 4 0
|