public BesuControllerBuilder metricsSystem(final ObservableMetricsSystem metricsSystem) {
    this.metricsSystem = metricsSystem;
    return this;
  }
Metrics system besu controller builder.

@param metricsSystem the metrics system
@return the besu controller builder
app/src/main/java/org/hyperledger/besu/controller/BesuControllerBuilder.java