Object Casting in a JSP

Question

When getting data from the usual HttpSession object, I understand how the following (for simplicity) hypothetical line of code works:
AccountInfo someAccount = (AccountInfo) session.getAttribute( ... );
Here, assume that "AccountInfo" is a bean i.e., implements serializable and has standad getters and setters. So far nothing special but wait... What about the following variation:
AccountInfo someAccount = (AccountInfo) (List) session.getAttribute( ... );
The surprising thing was that the someAccount object has its data populated with items from the list! Why do I say such silly things? Well the code that follows leads me to that conclusion:
AccountInfo someAccount = (AccountInfo) (List) session.getAttribute( ... );
this.doSomething(accInfo);
It's not obvious to me when the getters and setters of accInfo were called?? Can someone provide an explanation? I was not aware of this mechanism. Should I get a new Java book?
Thanks!

Answer 1

EDITED VERSION OF THE ABOVE POST
When getting data from the usual HttpSession object, I understand how the following hypothetical line of code works:
AccountInfo someAccount = (AccountInfo) session.getAttribute( ... );
Here, assume that "AccountInfo" is a bean i.e., implements serializable and has standad getters and setters. So far nothing special but wait... What about the following variation (I saw something like this in some code at work)
AccountInfo someAccount = (AccountInfo) (List) session.getAttribute( ... );
So its just two sequential casts, right? What surprised me, was that the someAccount bean has its data populated with items from the list! Can someone provide an explanation? I was not aware of this mechanism. Should I get a new Java book?
Thanks