Get viewer of a View Eclipse

Question

I try to refresh my Sirius Project programmatically like it refreshs if I'm press F5. project.refreshLocal(IResource.DEPTH_INFINITE, new NullProgressMonitor()) doesn't refresh the project the way I want, so I checked out what the org.eclipse.ui.actions.RefreshAction does. I found out that org.eclipse.ui.actions.RefreshAction use the following code snippet

shell.getDisplay().asyncExec(new Runnable() {

     @Override
     public void run() {
        StructuredViewer viewer = getActionSite().getStructuredViewer();
            if (viewer != null && viewer.getControl() != null && !viewer.getControl().isDisposed()) {
                viewer.refresh();
            }
        }
});

to refresh the modelexplorer view like i want to. My problem right now is that I got the modelexplorer view, but don't know how I access the viewer from it, to refresh the view. Does anyone got any clue how to do it?