implementation/Common-class-walkthrough.md

@@ -110,3 +110,20 @@ public static String getAASServerPath() {
 }
 ```
 This method returns the value of the environment variable `AASSERVERPATH` or a fallback, handling the acquisition of the value very similar to the method above.
+
+```java
+public static String getMQTTBrokerHost() {
+    String uncheckedMQTTBrokerHost = System.getenv("MQTTBROKERHOST");
+    if (uncheckedMQTTBrokerHost == null || uncheckedMQTTBrokerHost.isEmpty()) {
+        logger.warn("No valid MQTTBROKERHOST set.");
+        logger.warn("You might want to explicitly set a MQTTBROKERHOST environment variable, eg:");
+        logger.warn("$ export MQTTBROKERHOST=\"tcp://esp-controller.local:1883\"");
+        logger.warn("An MQTT broker at tcp://esp-controller.local:1883 will be assumed going forward.");
+        return "tcp://esp-controller.local:1883";
+    } else {
+        return "tcp://" + uncheckedMQTTBrokerHost + ":1883";
+    }
+}
+
+```
+This method returns the value of the environment variable `MQTTBROKERHOST` or a fallback, handling the acquisition of the value very similar to the method above.
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