title: spring sleuth baggage propagation not getting propagated/working
body: <p>We are currently using sleuth 2.2.3.RELEASE, and we couldn't see the field userId passed in http headers are not propagating. Below is our code.</p>
  <pre><code>BaggageField REQUEST_ID = BaggageField.create(&quot;x-vcap-request-id&quot;);
      BaggageField USER_ID = BaggageField.create(&quot;userId&quot;);
      
      Tracing.newBuilder().propagationFactory(
              BaggagePropagation.newFactoryBuilder(B3Propagation.FACTORY)
              .add(SingleBaggageField.remote(REQUEST_ID))
              .add(SingleBaggageField.newBuilder(USER_ID).addKeyName(&quot;baggage-user-id&quot;).build())
              .build());
  </code></pre>
  <p>We doubt that some issue in YML file. We tried with all the below options but none is working.</p>
  <pre><code>#1 baggage-keys: baggage-user-id 
  #2 propagation-keys: baggage-user-id
  #3 baggage-keys: user-id 
  </code></pre>
  <p>In logback:</p>
  <p>%X{baggage-user-id:-}</p>
  <p>We are passing userId as in http header.</p>