code: protected static ThreadMXBean getBean() {
          if (PreciseTime.bean == null)
              PreciseTime.bean = ManagementFactory.getThreadMXBean();
          return PreciseTime.bean;
      }
docs: Gets ThreadMXBean, creates one from {@link java.lang.management.ManagementFactory} if {@link #bean} is null.
  
  @return ThreadMXBean for precise time