/usr/share/gwyddion/gradients/Green is in gwyddion-common 2.38-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4
Gwyddion resource GwyGradient 0 0 0 0 1 0.5 0 1 0 1 1 1 1 1 1