How to use a session parameter in Page Composer EL expression

Summary:

We're working on Sandbox Configure Business Objects. Weve created a filed trigger and we set a session parameter with "adf.userSession.userData.put" method. Now we need to default a field value with this parameter using page composer but we need to know how to do this defaulting in the field EL expression.

Our scenario is actually, we place a "default salary value" in position definition Budget amount. When we're adding a new pending worker, we need to retrieve this default salary value from the PWK's selected position and default it in the New salary field.

We were able to retrieve the value from the related position and set the session variable accordingly, but we couldn't use it in the page composer EL expression.