public static DBSObject getSelectedObject(ISelection selection)
    {
        if (selection.isEmpty() || !(selection instanceof IStructuredSelection)) {
            return null;
        }
        return DBUtils.getFromObject(((IStructuredSelection)selection).getFirstElement());
    }
Find selected node for specified UI element
@param element ui element
@return node or null
plugins/org.jkiss.dbeaver.ui.navigator/src/org/jkiss/dbeaver/ui/navigator/NavigatorUtils.java