It seems like the Creating a UI Extension Link inside the Vaadin 7 wiki:
https://vaadin.com/wiki/-/wiki/Main/Vaadin+7
is broken as it’s pointing a this monstrosity of a link:
https://vaadin.com/wiki?p_p_id=36&p_p_lifecycle=0&p_p_state=normal&p_p_mode=view&p_p_col_id=row-1&p_p_col_pos=1&p_p_col_count=3&_36_struts_action=%2Fwiki%2Fedit_page&_36_redirect=https%3A%2F%2Fvaadin.com%2Fwiki%2F-%2Fwiki%2FMain%2FVaadin%2B7&p_r_p_185834411_nodeId=10674&p_r_p_185834411_title=Creating+a+UI+extension
while the original one is still present here:
https://vaadin.com/wiki/-/wiki/Main/Creating%20an%20UI%20extension
Is this meant to be?