- when the unit of the group by start date value is null, the interval for the group by start date is automatically selected
- the previous point is documented in the REST-API wiki
- the automatic interval selection works as follows:
- it finds out what is the min and max value of the data is and based divides it by 80 to get 80 data points in total.
- in case the there is only one data point or none, the date interval by default is month and an info log that says it was not possible to auto-create a useful interval
- if a unit is provided, the group by start date works as before