code: void markCommandStart(HystrixCommandKey commandKey, HystrixThreadPoolKey threadPoolKey, HystrixCommandProperties.ExecutionIsolationStrategy isolationStrategy) {
          int currentCount = concurrentExecutionCount.incrementAndGet();
          HystrixThreadEventStream.getInstance().commandExecutionStarted(commandKey, threadPoolKey, isolationStrategy, currentCount);
      }
docs: /* package-private