anchor.diff:  .The setup
   [source,yml]
   ----
  -Unresolved directive in intro.adoc - include::{project-root}/spring-cloud-sleuth-core/src/test/resources/application-baggage.yml[indent=0]
  +spring.sleuth:
  +  baggage-keys:
  +    - baz
  +    - bizarrecase
  +  propagation-keys:
  +    - foo
  +    - upper_case
   ----
   
   .The code
   [source,java]
   ----
  -Unresolved directive in intro.adoc - include::{project-root}/spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/multiple/MultipleHopsIntegrationTests.java[tags=baggage_tag,indent=0]
  +initialSpan.tag("foo",
  +		ExtraFieldPropagation.get(initialSpan.context(), "foo"));
  +initialSpan.tag("UPPER_CASE",
  +		ExtraFieldPropagation.get(initialSpan.context(), "UPPER_CASE"));
   ----
   
   [[sleuth-adding-project]]
  
positive.code: 
  [source,java]
  ----
  Unresolved directive in intro.adoc - include::{project-root}/spring-cloud-sleuth-zipkin/src/test/java/org/springframework/cloud/sleuth/zipkin2/ZipkinAutoConfigurationTests.java[tags=override_default_beans,indent=0]
  ----
  
  == Additional Resources
  
negative.code: 
  [source,java]
  ----
  Span initialSpan = this.tracer.nextSpan().name("span").start();
  ExtraFieldPropagation.set(initialSpan.context(), "foo", "bar");
  ExtraFieldPropagation.set(initialSpan.context(), "UPPER_CASE", "someValue");
  ----
  
  ===== Baggage versus Span Tags
  