A closed time interval. It extends from the start time to the end
time, and includes both: [startTime, endTime]. Valid time
intervals depend on the `MetricKind </monitoring/api/ref_v3/rest/v
3/projects.metricDescriptors#MetricKind>__ of the metric value. In no
case can the end time be earlier than the start time. - For aGAUGEmetric, thestartTimevalue is technically optional;
if no value is specified, the start time defaults to the value of
the end time, and the interval represents a single point in time.
If both start and end times are specified, they must be identical.
Such an interval is valid only forGAUGEmetrics, which are
point-in-time measurements. - ForDELTAandCUMULATIVE`
metrics, the start time must be earlier than the end time. - In
all cases, the start time of the next interval must be at least a
millisecond after the end time of the previous interval. Because the
interval is closed, if the start time of a new interval is the same
as the end time of the previous interval, data written at the new
start time could overwrite data written at the previous end time.
.. attribute:: end_time
Required. The end of the time interval.