Compare items in an existing list based on property in HQL

Let say I have two class:

public class A{

 public virtual int Id;
 ...开发者_运维问答
 ...

}

public class B{

   public virtual int Id;

   public virtual A a;
 ...

}

I have a list of A. List existingObjectAList;

and also I want to search object B's which contains existingObjectAList.

How can I do this In C# with HQL.

---

var bs = session.CreateQuery("from B where A in (:list)"
                .SetParameterList("list", existingObjectAList)
                .List<B>();