[RUN-5058] Document the Java tracing API (11.10.0)

content/en/docs/refguide/runtime/tracing-in-runtime.md

@@ -165,3 +165,39 @@ You can also collect metrics data (CPU load, memory, etc.) and logs using OpenTe
 
 * See the [OpenTelemetry](/refguide/metrics/#opentelemetry) section of *Metrics* for a guide on how to setup metrics with OpenTelemetry.
 * See [Request to Create New Log Subscriber in Open Telemetry Format](/refguide/monitoring-mendix-runtime/#new-log-sub-opentelemetry) in *Monitoring Mendix Runtime* for a guide on how to setup logs with OpenTelemetry.
+
+## Custom Spans in Java Actions
+
+{{% alert color="info" %}}
+Custom spans in Java actions was introduced in Mendix 11.10.0.
+{{% /alert %}}
+
+Custom spans can be created in Java actions using the `Core.tracing()` API.
+
+Below is an example of how to create a span and wrap some code in it. The `run` method starts and closes the span, sets the span status and handles exceptions.
+
+```java
+Core.tracing()
+  .createSpan("my span name")
+  .withAttribute("attribute key", "attribute value")
+  .run(span -> {
+    // the code here will be wrapped by the span
+  });
+```
+
+If the flow of control is more complicated, then you can also handle the lifecycle of the span manually using the `start` and `close` methods.
+
+```java
+var span = Core.tracing()
+  .createSpan("my span name")
+  .withAttribute("attribute key", "attribute value")
+  .start();
+try {
+  // your code
+  span.setStatus(Span.Status.OK);
+} catch (Throwable exc) {
+  span.setError(exc);
+} finally {
+  span.close();
+}
+```