Oh the default ESGG scenery is definitely strange. The parking position you used has no jetway, the scenery author didn't place them. There are some on other positions though:
EDIT: Comparing that with the real airport it looks like that the author tried to simulate the fixed jetways that are present at the real airport with this construction without actually using an X-Plane jetway:
I opend a bug report for you: https://gateway.x-plane.com/bug_reports?selected_issue=XSG-11307