@Override
    public String toString() {
        return "ImmutableMetrics{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", counts=" + counts +
                ", durationNs=" + durationNs +
                '}';
    }
A {@link Metrics} implementation that cannot be modified.

@author Bob Briody (http://bobbriody.com)
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/util/ImmutableMetrics.java