/// <summary>
/// Sets the current entity set's <see cref="ParentExpression"/> to the specified <paramref name="expression"/>.
/// </summary>
/// <param name="expression">
/// The expression to set as the parent expression.
/// </param>
/// <typeparam name="TExpression">
/// The type of entity selected by the expression.
/// </typeparam>
public void WithAs <TExpression>(EntityExpression <TExpression> expression)
{
this.ParentExpression = expression ?? throw new ArgumentNullException(nameof(expression));
}