code: public static void createAndRegister(
        SpanBytesEncoder encoder, Sender sender, String serviceName) {
      ZipkinTraceExporter.createAndRegister(encoder, sender, serviceName);
    }
docs: Creates and registers the Zipkin Trace exporter to the OpenCensus library. Only one Zipkin
  exporter can be registered at any point.
  
  @param encoder Usually {@link SpanBytesEncoder#JSON_V2}
  @param sender Often, but not necessarily an http sender. This could be Kafka or SQS.
  @param serviceName the {@link Span#localServiceName() local service name} of the process.
  @throws IllegalStateException if a Zipkin exporter is already registered.
  @since 0.8