This represents a sample as found in the text data. This may or may not represent
a full metric. In the case of a counter or gauge, it will represent the full metric.
In the case of a summary or histogram, this only represents one quantile or one bucket
in a full summary or histogram metric. For those two cases, additional processing needs to
be made to combine multiple TextMetric objects into a single SummaryMetric or HistogramMetric.