/// <summary>
/// When the event is fired in this state, execute the chained activities
/// </summary>
/// <param name="fact"></param>
/// <param name="conditionalExpression"></param>
/// <returns></returns>
protected void When <T>(Fact <T> fact, Expression <Func <T, bool> > conditionalExpression)
where T : class
{
var ruleFact = _factCache[fact.Name] as IRuleFact <T>;
if (ruleFact == null)
{
throw new ArgumentException($"The fact is unknown or has not been declared: {fact.Name}", nameof(fact));
}
var condition = _expressionConverter.GetRuleCondition(ruleFact, conditionalExpression);
_conditions.Add(condition);
}