@Nullable
  private PsiClass resolveQualifier() {
    return CachedValuesManager.getCachedValue(this, () -> {
      GrCodeReferenceElement reference = getImportReference();
      GrCodeReferenceElement qualifier = reference == null ? null : reference.getQualifier();
      PsiElement target = qualifier == null ? null : qualifier.resolve();
      PsiClass clazz = target instanceof PsiClass ? (PsiClass)target : null;
      return CachedValueProvider.Result.create(clazz, PsiModificationTracker.MODIFICATION_COUNT, this);
    });
  }
@Nullable
  private PsiClass resolveQualifier()