Parameters
- key
- The Key of the sampled metric definition to get (composed of the metrics system, category name, and counter name combined as a single string).
- value
- The output variable to receive the SampledMetricDefinition object if found (null if not).
Return Value
False if no metric definition is registered with the given Key, true if a SampledMetricDefinition is registered with the given Key, or throws an exception if the registered definition is not a SampledMetricDefinition.