code: public Metrics metric(final String name, final Metric metric) {
      bindings.add((binder, routes, conf) -> {
        MapBinder.newMapBinder(binder, String.class, Metric.class).addBinding(name)
            .toInstance(metric);
      });
      return this;
    }
docs: Append a metric to the {@link MetricRegistry}, this call is identical to
  {@link MetricRegistry#register(String, Metric)}.
  
  @param name Name of the metric.
  @param metric A metric object
  @return This metrics module.