Generator does not work with Jenkins' tighter CSRF protection

[scymtym]

What did you do?

This happens whenever the generator tries to modify something through Jenkins' HTTP API:

build-generator generate …
…
No valid crumb was included in the request</pre></p><hr><a href="http://eclipse.org/jetty">Powered by Jetty:// 9.4.z-SNAPSHOT</a><hr/>

Which behavior did you expect?
The request should succeed.

What happened instead?
Jenkins did not accept the CSRF protection token.

This seems to be caused by a Jenkins change that requires the session id cookie to be present in addition to a valid CSRF protection token.