- Statsd allows users to provide a metric with the same name but
differing types (counter, gauge, timer)
- The exporter allows this by letting users specify a
"match_metric_type" in the mapping config
- However the mapper cache does not look at the metric type so it would
return a MetricMapperCacheResult for the type of the first metric with
that name that the exporter saw
- Add MetricType to the signature for the cache and format the metric
name with the type to provide unique keys for a metric with the same
name but differing type
Signed-off-by: Andy Paine <andy.paine@digital.cabinet-office.gov.uk>