/**
     * Publishes an event to all instances.
     *
     * @param eventName the event name.
     * @param data optional event data.
     */
    public void publishEvent(final String eventName, final String data) {
        publishEvent(eventName, TARGET_ALL, data);
    }

    /**
     * Publishes an event to a specific instance or all instances.
     *
     * @param eventName the event name.

        final AtomicReference<String> capturedBody = new AtomicReference<>();
        final CoordinatorHelper helper = createCapturingHelper("node1@host1", null, capturedBody, createMockResponse(201, "{}"));

        helper.publishEvent("config_updated", "node2@host2", "web_config");

        assertNotNull(capturedBody.get());
        final Map<String, Object> body = coordinatorHelper.parseJson(capturedBody.get());