register method Null safety

void register(
  1. Metric metric
)

Register Metrics to make them visible to developer tooling.

Implementation

static void register(Metric metric) {
  // TODO: When NNBD is complete, delete the following line.
  ArgumentError.checkNotNull(metric, 'metric');
  if (_metrics[metric.name] != null) {
    throw ArgumentError('Registered metrics have unique names');
  }
  _metrics[metric.name] = metric;
}