Merge branch '3.1.x'

Closes gh-36113

spring-boot-project/spring-boot-docs/src/docs/asciidoc/actuator/tracing.adoc

@@ -171,3 +171,18 @@ include::code:CustomObservation[]
 This will create an observation named "some-operation" with the tag "some-tag=some-value".
 
 TIP: If you want to create a span without creating a metric, you need to use the https://micrometer.io/docs/tracing#_using_micrometer_tracing_directly[lower-level `Tracer` API] from Micrometer.
+
+[[actuator.micrometer-tracing.baggage]]
+=== Baggage
+You can create baggage with the `Tracer` API:
+
+include::code:CreatingBaggage[]
+
+This example creates baggage named `baggage1` with the value `value1`.
+The baggage is automatically propagated over the network if you're using W3C propagation.
+If you're using B3 propagation, baggage is not automatically propagated.
+To manually propagate baggage over the network, use the configprop:management.tracing.baggage.remote-fields[] configuration property (this works for W3C, too).
+For the example above, setting this property to `baggage1` results in an HTTP header `baggage1: value1`.
+
+If you want to propagate the baggage to the MDC, use the configprop:management.tracing.baggage.correlation.fields[] configuration property.
+For the example above, setting this property to `baggage1` results in an MDC entry named `baggage1`.