class ActionReturnSseHandler implements ActionReturnHandler {
    @Override
    public boolean matched(Class<?> returnType) {
        return SseEmitter.class.isAssignableFrom(returnType);
    }

    @Override
    public void returnHandle(Context ctx, Action action, Object returnValue) throws Throwable {<FILL_FUNCTION_BODY>}
}

        if (returnValue != null) {
            if (ctx.asyncSupported() == false) {
                throw new IllegalStateException("This boot plugin does not support asynchronous mode");
            }

            new SseEmitterHandler((SseEmitter) returnValue).start();
        }
    
<no_super_class>