code: @SuppressWarnings("unchecked")
      public static <S extends ArtifactCollector<? extends ArtifactType>> Optional<S>
                      getWatcher(Description description, Class<S> watcherType) {
          List<ArtifactCollector<? extends ArtifactType>> watcherList = watcherMap.get(description);
          if (watcherList != null) {
              for (ArtifactCollector<? extends ArtifactType> watcher : watcherList) {
                  if (watcher.getClass() == watcherType) {
                      return Optional.of((S) watcher);
                  }
              }
          }
          return Optional.absent();
      }
docs: Get reference to an instance of the specified watcher type associated with the described method.
  
  @param <S> type-specific artifact collector class
  @param description JUnit method description object
  @param watcherType watcher type
  @return optional watcher instance