modules/jooby-metrics/src/main/java/org/jooby/metrics/Metrics.java
public Metrics reporter(final BiFunction<MetricRegistry, Config, Reporter> callback) {
    this.reporters.add(requireNonNull(callback, "Callback is required."));
    return this;
  }
public Metrics reporter(final BiFunction<MetricRegistry, Config, Reporter> callback) {
    this.reporters.add(requireNonNull(callback, "Callback is required."));
    return this;
  }
Append a {@link Reporter} to the {@link MetricRegistry}.

@param callback Reporter callback.
@return This metrics module.