* Point to the convenience functions in api/key package
This is to increase the visibility of the api/key package through the
api/core package, otherwise developers often tend to miss the api/key
package altogether and write `core.Key(name).TYPE(value)` and complain
at the verbosity of such a construction. The api/key package would
allow them to write `key.TYPE(name, value)`.
* Use the api/key package where applicable
This transforms all the uses of `core.Key(name).TYPE(value)` to
`key.TYPE(name, value)`. This also should help increasing the
visibility of the api/key package for developers reading the otel-go
code.
Co-authored-by: Joshua MacDonald <jmacd@users.noreply.github.com>
Instead of batching based on the Resource pointer which is not guaranteed
to uniquely identify common Resources, use the `String` method which is.
Renames the external test package to be identified as the integration
testing. This testing structure (the mock exporter) batches exported
resources transmitted from the resource. This is needed as there is no
guarantees that a batch will be exported in a single payload, therefore,
it is not an ideal place to add resource batch testing for the exporter
itself.
Add unit tests to ensure the Exporter is correctly batching spans by
resource.
