setSelectedIndex of JBlist in PopupChooserBuilder

Hi,
i am trying to add a popup with options to my plugin. Using PopupChooserBuilder with a prepopulated JBList, i managed to create and display the options correctly. Now i want one specific option to be preselected.
I tried using: list.setSelectedIndex(idSelectedItem);
prior to creation the popupChooser via: new PopupChoserBuilder(list);
unfortunately this seems not to work. Also searching the forum did not help me finding out how to do it.

thanks in advance for your advice,
greetings, Kay