"is not a enum" error when Enum is not in his own file

[smotastic]

class FirstClass {
  // ...
}
@Enume()
enum FirstClassEnum { foo, bar }

This will result in an error
'FirstClassEnum is not a enum and cannot be annotated with @\Enume()'

I guess the Problem is this check here

!EnumValidator.isEnum(element.enclosingElement)

As a workaround i put the enum in it's own dart file, but would be nice if i can put it together with the other class.