@Override
  public @NotNull PsiReferenceExpression createReferenceExpression(@NotNull PsiPackage aPackage) throws IncorrectOperationException {
    if (aPackage.getQualifiedName().isEmpty()) {
      throw new IncorrectOperationException("Cannot create reference to default package.");
    }
    return new LightPackageReferenceExpression(myManager, aPackage);
  }
@Override
  public @NotNull PsiReferenceExpression createReferenceExpression(@NotNull PsiPackage aPackage)