WebApplication.unmount(String) doesn't work if invoked from Application#init() (or IInitializer#init())

java.lang.IllegalArgumentException: Argument 'requestCycle' may not be null.
at org.apache.wicket.util.lang.Args.notNull(Args.java:41)
at org.apache.wicket.Application.fetchCreateAndSetSession(Application.java:1516)
at org.apache.wicket.Session.get(Session.java:159)
at org.apache.wicket.request.mapper.BufferedResponseMapper.getSessionId(BufferedResponseMapper.java:48)
at org.apache.wicket.request.mapper.BufferedResponseMapper.getAndRemoveBufferedResponse(BufferedResponseMapper.java:58)
at org.apache.wicket.request.mapper.BufferedResponseMapper.mapRequest(BufferedResponseMapper.java:85)
at org.apache.wicket.request.mapper.CompoundRequestMapper.unmount(CompoundRequestMapper.java:193)
at org.apache.wicket.protocol.http.WebApplication.unmount(WebApplication.java:374)
at com.mycompany.WicketApplication.init(WicketApplication.java:22)
at org.apache.wicket.Application.initApplication(Application.java:807)
at org.apache.wicket.protocol.http.WicketFilter.init(WicketFilter.java:346)
at org.apache.wicket.protocol.http.WicketFilter.init(WicketFilter.java:286)

BufferedResponseMapper tries to create a session in non-http thread.