@NotNull
  private static Collection<GroovyResolveResult> getSuperClass(@NotNull PsiClass aClass) {
    PsiClass superClass = aClass.getSuperClass();
    if (superClass != null) {
      PsiSubstitutor superClassSubstitutor = TypeConversionUtil.getSuperClassSubstitutor(superClass, aClass, PsiSubstitutor.EMPTY);
      return Collections.singletonList(new GroovyResolveResultImpl(superClass, null, null, superClassSubstitutor, true, true));
    }
    else {
      return Collections.emptyList(); //no super class, but the reference is definitely super-reference
    }
  }
@NotNull
  private static Collection<GroovyResolveResult> getSuperClass(@NotNull PsiClass aClass)