public ApolloAuditSpan getActiveSpan() {
    ApolloAuditSpan activeSpan = getActiveSpanFromContext();
    if (activeSpan != null) {
      return activeSpan;
    }
    activeSpan = getActiveSpanFromHttp();
    // might be null, root span generate should be done in other place
    return activeSpan;
  }
@Test
  public void testGetActiveSpanFromHttpRequestCaseNotInRequestThread() {
    {
      // no span would be in context
      Mockito.when(manager.activeSpan()).thenReturn(null);
      // not in request thread
    }
    ApolloAuditSpan get = tracer.getActiveSpan();
    assertNull(get);
  }