ModelDriven does not update model for property List that was emptied

[Jonilie Echavez]

My JSP has a property i will call as 'itemList', which i allow to be emptied if user wants to remove items to it.
This property is set with initial values from what is stored in the database. So initially, itemList will have values [avocado,tomato].

THe JSP page allows add,update,or delete in itemList.

 requestJSON[itemList]=optionList; 

where optionList may or may have values in it.

Debugging using FireBug shows that the values are set correctly in the following instances:

Example:
a) when user has picked or updated values for itemList
itemList = [avocado,salmon]
b) when user has has removed all items
itemList = []

However when i debug the action class that receives the model, it does update the property when the condition is in example (a), but not when it's (b).
When it's (b), the itemList still stores the previous value of the itemList=[avocado,tomato].

Is this a behaviour of ModelDriven, or what am i missing?

Appreciate your help.