Hard dependency on io.dropwizard.metrics:metrics-core cannot be avoided

The metrics subsystem has a hard dependency on io.dropwizard.metrics:metrics-core that cannot be avoided because of this code:

public final class ServerMetrics {
/**

• Dummy instance useful for tests.
  */
  public static final ServerMetrics DEFAULT_METRICS_FOR_TESTS = new ServerMetrics(new DefaultMetricsProvider());

Even if the config metricsProvider.className=org.apache.zookeeper.metrics.impl.NullMetricsProvider is set the above code will still execute and create the dependency.

It would be best to make the dependency optional by removing the above code.

Another option is to change the dependency scope from the current value of "provided" to be "compile" instead.