After #21798, messages on the clientInboundChannel can be handled sequentially within a session by setting StompEndpointRegistry#preserveReceiveOrder. This in addition to the MessageBrokerRegistry#preservePublishOrder that does the same for messages on the clientOutboundChannel.
UserDestinationMessageHandler subscribes to clientInboundChannel and brokerChannel and also handles messages from the client. Therefore it makes sense to extend the support for StompEndpointRegistry#preserveReceiveOrder so when it is enabled, messages with user destinations are handled sequentially by user.