title: Return trace id from Jaeger in response header
body: <p>I am using opentelemetry in my python FastAPI application.
  It sends traces back to Jaeger.
  Each trace has a unique trace id I can also search for in the Jaeger UI search bar.</p>
  <p>I want to return in the response headers that trace id so that later on I can look a trace for a specific request (just take the trace id from the header and search for it in Jaeger UI).</p>
  <p>I tried adding a middleware in FastAPI that adds the trace id like that -</p>
  <pre><code>class EnrichOpenTelemetryId(BaseHTTPMiddleware):
      def __init__(self, app):
          super().__init__(app)
  
      async def dispatch(self, request: Request, call_next):
          with tracer.start_span(&quot;dummy-span&quot;) as span:
              trace_id = str(span.get_span_context().trace_id)
  
          response = await call_next(request)
          response.headers[&quot;X-Trace-Id&quot;] = trace_id
  
          return response   
  
  </code></pre>
  <p>There is a new header containing some trace id (e.g - 149906749482483391829634904508866243046) in each request but it's not the one Jaeger uses... (meaning I cannot search on that trace id).
  Jaeger trace id looks something like that - 8eddc793de380fa76c54557af09538e3.</p>
  <p>So how do I get Jaeger trace id?</p>