public void onStartWithServer(ExecutionContext<I> context, ExecutionInfo info) {
        for (ExecutionListener<I, O> listener: listeners) {
            try {
                if (!isListenerDisabled(listener)) {
                    listener.onStartWithServer(context.getChildContext(listener), info);
                }
            } catch (Throwable e) {
                if (e instanceof AbortExecutionException) {
                    throw (AbortExecutionException) e;
                }
                logger.error("Error invoking listener " + listener, e);
            }
        }
    }
Called when a server is chosen and the request is going to be executed on the server.
ribbon-loadbalancer/src/main/java/com/netflix/loadbalancer/reactive/ExecutionContextListenerInvoker.java