code: public HystrixMetricsPublisherThreadPool getMetricsPublisherForThreadPool(HystrixThreadPoolKey threadPoolKey, HystrixThreadPoolMetrics metrics, HystrixThreadPoolProperties properties) {
          return new HystrixMetricsPublisherThreadPoolDefault(threadPoolKey, metrics, properties);
      }
docs: Construct an implementation of {@link HystrixMetricsPublisherThreadPool} for {@link HystrixThreadPool} instances having key {@link HystrixThreadPoolKey}.
  <p>
  This will be invoked once per {@link HystrixThreadPoolKey} instance.
  <p>
  <b>Default Implementation</b>
  <p>
  Return instance of {@link HystrixMetricsPublisherThreadPoolDefault}
  
  @param threadPoolKey
  {@link HystrixThreadPoolKey} representing the name or type of {@link HystrixThreadPool}
  @param metrics
  {@link HystrixThreadPoolMetrics} instance tracking metrics for the {@link HystrixThreadPool} instance having the key as defined by {@link HystrixThreadPoolKey}
  @param properties
  {@link HystrixThreadPoolProperties} instance for the {@link HystrixThreadPool} instance having the key as defined by {@link HystrixThreadPoolKey}
  @return instance of {@link HystrixMetricsPublisherThreadPool} that will have its <code>initialize</code> method invoked once.