Variables in interfaces are always public static final.
From the JLS, 9.3 Field (Constant) Declarations
Every field declaration in the body of an interface is
implicitly public, static, and final.
So these three modifiers, public, static and final, are
redundant in interfaces.
When the module RedundantModifier is used, checkstyle
complains about public and final but not about static.
I think, checkstyle should also complain about static.