Currently most of our metrics save their metric specific results in a section called Results. This is a 'top level' entry in the JSON.
Individually this is fine, but when we start to gather these metrics into a database, some databases (I am specifically thinking of elasticsearch here), require that each unique named data item (the full name to the data item in JSON iyswim) holds a single data type. That is for instance you cannot have say Result.average being stored with both ints and strings.
I've not seen that we have a problem at present, but, I think there is a strong risk our test results will one day clash in their namespace/types, and then we will fail to store them (elastic will reject the data injection for instance).
I think the fix here is to place all test specific generated data into a subsection. And that section can be named according to the already unique TEST_NAME var from the tests. That should isolate any one specific tests result layout data from any other, and avoid the issue altogether.