Local class names of (public static) inner classes are not resolved uniformly when looking up type declarations during the pattern compilation process
That is:

class Bar { public static class Foo {} }
declare Foo @role(event) end
rule X when Foo() then end

the "declared" type is resolved as Bar.Foo in package com.sample, while the pattern looks for the declaration of Foo in the sampe package.
(Notice that the fully qualified name is the same instead)