Clarification on model metric of exporter.export(batch)

[legendecas]

What are you trying to achieve?

Export(batch)

Exports a batch of Metrics. Protocol exporters that will implement this function are typically expected to serialize and transmit the data to the destination.
Parameters:
batch - a batch of Metrics. The exact data type of the batch is language specific, typically it is some kind of list.
https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/sdk.md#exportbatch

The type name Metrics is not mentioned anywhere else (as far as I can tell, I didn't find anything at https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/datamodel.md) and it is unclear what it contains.

[reyang]

It is not specified, but it has to be a stable API. It is "based on" the data model, it should not be based on the Proto generated data types.

[reyang]

@legendecas based on the discussion from 11/2/2021 Spec SIG Meeting, I've added clarification in #2106. Please take a look.