I get this message when render a collection. "Caught an exception while evaluating expression 'contacts.size()==0' against value stack
java.lang.NullPointerException: target is null for method size"
The contacts is a collection of contact's of selected user. For verify the content of collection contacts, before return success, I add a simple iterator in method and printing in console all objects the collection, and this goes fine.
In action I have setter/getter of contact