code: public static void createAndRegister(String v2Url, String serviceName) {
      createAndRegister(SpanBytesEncoder.JSON_V2, URLConnectionSender.create(v2Url), serviceName);
    }
docs: Creates and registers the Zipkin Trace exporter to the OpenCensus library. Only one Zipkin
  exporter can be registered at any point.
  
  @param v2Url Ex http://127.0.0.1:9411/api/v2/spans
  @param serviceName the {@link Span#localServiceName() local service name} of the process.
  @throws IllegalStateException if a Zipkin exporter is already registered.
  @since 0.12