SpineTest routines to switching skin?

See SpineTest today, very happy. But also encounter some problems, need to consult.
SpineTest routines, a configuration file spineboy.json, a project “skins” in the file, there are two lines of code to the project
Eyes
{
Eyes {X 28.94, Y rotation ~~32.92,~~86.9, width height 34, 27},
Eyes-closed {X 28.77, Y rotation ~~32.86,~~86.9, width height 34, 27}
},

I would like to ask, this how to switch the display?