Illustrate how to register a standalone event subscriber.

src/main/java/io/spine/helloworld/server/hello/HelloContext.java

@@ -52,6 +52,8 @@ private HelloContext() {
     public static BoundedContextBuilder newBuilder() {
         return BoundedContext
                 .singleTenant(NAME)
-                .add(Console.class);
+                .add(Console.class)
+                // Plug a standalone event dispatcher into this Bounded Context.
+                .addEventDispatcher(new ListenerOfPrinted());
     }
 }

src/main/java/io/spine/helloworld/server/hello/ListenerOfPrinted.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2023, TeamDev. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package io.spine.helloworld.server.hello;
+
+import io.spine.core.Subscribe;
+import io.spine.helloworld.hello.event.Printed;
+import io.spine.server.event.AbstractEventSubscriber;
+import io.spine.string.Stringifiers;
+
+import static java.lang.String.format;
+
+/**
+ * Listens to {@link io.spine.helloworld.hello.event.Printed Printed} events.
+ */
+final class ListenerOfPrinted extends AbstractEventSubscriber {
+
+    /**
+     * Subscribes to {@code Printed} domain events.
+     *
+     * <p>This is a no-op implementation. In real life, Spine end-users
+     * may choose to send this event (or whichever they subscribe to)
+     * down their pipeline, including any external systems, such as Kafka.
+     *
+     * @param event an event emitted somewhere outside of this subscriber
+     */
+    @Subscribe
+    @SuppressWarnings({
+            "UseOfSystemOutOrSystemErr" /* To print out the event in its simplest form. */,
+            "unused" /* This method is invoked by Spine framework. */})
+    void on(Printed event) {
+        String message = format("[Listener of `Printed`] An event is received: %s",
+                               Stringifiers.toString(event));
+        System.out.println(message);
+    }
+}