code: BraveSpan currentSpan() {
      BraveScope scope = currentScopes.get().peekFirst();
      if (scope != null) {
        return scope.span();
      } else {
        brave.Span braveSpan = tracer.currentSpan();
        if (braveSpan != null) {
          return new BraveSpan(tracer, braveSpan);
        }
      }
      return null;
    }
docs: Attempts to get a span from the current api, falling back to brave's native one