code: public static Collection<HystrixThreadPoolMetrics> getInstances() {
          List<HystrixThreadPoolMetrics> threadPoolMetrics = new ArrayList<HystrixThreadPoolMetrics>();
          for (HystrixThreadPoolMetrics tpm: metrics.values()) {
              if (hasExecutedCommandsOnThread(tpm)) {
                  threadPoolMetrics.add(tpm);
              }
          }
  
          return Collections.unmodifiableCollection(threadPoolMetrics);
      }
docs: All registered instances of {@link HystrixThreadPoolMetrics}
  
  @return {@code Collection<HystrixThreadPoolMetrics>}