See https://github.com/eclipse/jetty.project/blob/master/jetty-server/src/main/java/org/eclipse/jetty/server/AbstractConnector.java#L174 and https://github.com/eclipse/jetty.project/blob/master/jetty-server/src/main/java/org/eclipse/jetty/server/AbstractConnector.java#L184

If you want to pass in server.getThreadPool(), then you should unmanage it afterwards.