This is a defect regarding
WebsocketConsumer has service method where Atmosphere handle incoming request. In case value for enableEventsResending will be set after request is handled OnOpen event will not be sent at all.
Consequently, set this value should be before such as :
this.enableEventsResending = enableEventsResending;
In addition to this because of CamelWebSocketServlet use init method for set enableEventsResending value, tests which were written for this feature are wrong. To solve this a new TestSupport class should be created where init parameter will be set correctly and tests depending on this parameter will be moved to separate class which extend the new TestSupport class.