title: Adding custom trace id in sleuth
body: <p>I am using sleuth 2.0.x, I want to add my own trace id apart from its own.</p>
  
  <p>I`m going through the given link <br>
  <a href="https://cloud.spring.io/spring-cloud-static/spring-cloud-sleuth/2.0.0.RC2/single/spring-cloud-sleuth.html#_propagation" rel="nofollow noreferrer">https://cloud.spring.io/spring-cloud-static/spring-cloud-sleuth/2.0.0.RC2/single/spring-cloud-sleuth.html#_propagation</a></p>
  
  <p>I want to modify trace like below code:-
       public static final String TAG_NAME = "X-B3-CONVID";</p>
  
  <pre><code>@Bean
  @Order(TraceWebServletAutoConfiguration.TRACING_FILTER_ORDER + 1)
  public GenericFilterBean customTraceFilter(final Tracer tracer) {
      return new GenericFilterBean() {
  
          @Override
          public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
                  FilterChain filterChain) throws IOException, ServletException {
  
              Span span = tracer.currentSpan();
  
  
              String existingConversationId = span.getBaggage().get(TAG_NAME.toLowerCase());
  
              if(existingConversationId == null){
                  existingConversationId = UUID.randomUUID().toString();
                  span. setBaggageItem(TAG_NAME, existingConversationId);
              }
  
              tracer.addTag(TAG_NAME, existingConversationId);
              MDC.put(TAG_NAME, existingConversationId);
              tracer.continueSpan(span);
  
              filterChain.doFilter(servletRequest, servletResponse);
          }
      };
  }
  </code></pre>
  
  <p>But some functions like <strong>continueSpan, addTag, getBaggage</strong> removed from Sleuth 2.0.x.</p>
  
  <p>Any example for X-B3-CONVID?</p>