@Override
    public String toString() {
        return "Metric{" +
                "name='" + name + '\'' +
                ", outputName='" + outputName + '\'' +
                ", dimensions=" + dimensions +
                '}';
    }
Returns a new Metric that is a combination of this and the given metric.
New dimensions from the given metric are added, but already existing
dimensions will be kept unchanged.

@param other The metric to add dimensions from.
@return A new metric with dimensions from this and the other.
metrics/src/main/java/ai/vespa/metrics/set/Metric.java