@Test
void testExec_allClasses() {

    //Given
    //no regex so should get all classes back
    heapHistogramConfig.setClassNameMatchRegex("");
      mockStroomPropertyService.setProperty(HeapHistogramService.CLASS_NAME_MATCH_REGEX_PROP_KEY, "");
      Mockito.when(statisticsFactory.instance())
              .thenReturn(statistics);
    //When
    executor.exec();
    //Then
    Mockito.verify(mockInternalStatisticsReceiver, Mockito.timeout(5_000).times(2))
            .putEvents(eventsCaptor.capture());
    List<List<InternalStatisticEvent>> argValues = eventsCaptor.getAllValues();
    //We must have some classes in the list
    assertThat(argValues.get(0).size() > 0).isTrue();
    //the histo is duplicated as two separate stats so two lists of equal size
    assertThat(argValues.get(0).size() == argValues.get(1).size()).isTrue();
    //Ensure we have multiple starting letters of the class names to show a variety of classes are coming back
    for (List<InternalStatisticEvent> statisticEvents : argValues) {
        assertThat(statisticEvents.stream()
                .map(STAT_TO_CLASS_NAME_MAPPER)
                .map(className -> className.substring(0, 1))
                .distinct()
                .count() > 1).isTrue();
    }
}