@Override
    public Metric.Context createContext(Map<String, ?> properties) {
        Metric.Context[] contexts = new Metric.Context[consumers.length];
        for (int i = 0; i < consumers.length; ++i) {
            contexts[i] = consumers[i].createContext(properties);
        }
        return new ForwardingContext(contexts);
    }
If more than one {@link MetricConsumerFactory} is registered in a container, calls to <code>Metric</code> need to be
forwarded to all the underlying <code>MetricConsumers</code>. That is the responsibility of this class.
Instances of this class is created by the {@link MetricConsumerProvider} in those cases.

@author Simon Thoresen Hult
container-disc/src/main/java/com/yahoo/container/jdisc/metric/ForwardingMetricConsumer.java