Return a reference to the non-modifiable MetricSampleGroup object at the specified index in this sample.
The behavior is undefined unless 0 <= index < numGroups(). Note that the returned reference will remain valid until this sample is modified by invoking appendGroup or removeAllRecords().
non-modifiable reference to the sample group at index
| Name | Description |
|---|---|
| index | zero-based index of the sample group |