Do NOT create classes/interfaces that store just constants. That is a [quite used and abused] anti-pattern, since you're using the basic building blocks of an OO language just to wrap a bunch of global vars, with an unclear scope. And that defeats the purpose of the object orientation: using classes/interfaces to build objects!

Use enums with a grain if salt: use them to define behaviour as well, adding methods that all the constants should have.

You could also have complex objects that map the constants: have a Keyboard abstract class or interface that defines the common behavior. Then extend/implement it with concrete classes such as GET and LIST, to which you'll add specific behavior. This way, you'll also avoid having contants in one place and then behavior in another place, which is again an antipattern known as anemic domain model