Javadoc link for 9.x is broken

[Maxim Solodovnik]

Hello All,

While building wicketstuff-core I noticed lots of javadoc errors
Javadoc was unable to get wicket 9.x API from URL (
https://ci.apache.org/projects/wicket/apidocs/9.x/)

how this can be fixed?

-- 
WBR
Maxim aka solomax