With the help of CascadeChoiceParameter, PT_SINGLE_SELECT can fetch the value from Java server and then update it on the drop-down menu. But the value in Java server is not able to change the 2nd time. 

For example, a drop-down menu can display what user typed from input box. In other words, a drop-down menu is an referencedParameter with the input box. If user typed the word "First-Time", there will be a "First-Time" at the list of drop-down menu. But if user typed the word "Second-Time", the "First-Time" is still showing at the list of drop-down menu.

I have attached the source code and screenshot. Hope someone can take a look and figure out the problem. Thanks in advance.