Compile static: Groovyc reports error after instanceof check

@CompileStatic
class AnnotationCollectorChecker {
  boolean checkApplicability(PsiElement annotation) {
    final PsiElement parent = annotation.parent
    if (parent instanceof GrModifierList) {
      final collector = parent.rawAnnotations //compile error 'Access to com.intellij.psi.PsiElement#rawAnnotations'
      if (collector != null) {
        return true
      }
    }

    return false
  }
}