* Update OTLP to v0.4.0
* Update attribute transforms to use new KeyValue
* Update metric transforms
The labels are no longer included in the MetricDescriptor
Use new types.
* Fix OTLP integration tests
* Update example otel-collector go.sum
* Update metric integration testing
* Fix type error introduced in conflict resolution
* Deep clean of go.sum
Recreate go.sum for otel-collector example and OTLP exporter.
Update license header to standard format for source files missed prior.
Add license header to new source files.
Add Makefile check to test all `*.go` and `*.sh` files have a copyright
notice (or comment about them being auto-generated) within the first few
lines.
* Initial metrics addition to the OTLP exporter
* Fixes
Update to incorporate merged changes.
Fix lint issues.
* Add sum float64 transform unit test
* Fix static check
* Update comments
Fix malformed License header.
Add documentation for new transform functions.
Remove errant TODO.
* Fix test failures and handle ErrEmptyDataSet
Use `assert.NoError` instead of `assert.Nil` to correctly display
checked errors.
Use the result of `assert.NoError` to guard against `nil` pointer
dereferences.
Add check to skip `Record`s that return an `ErrEmptyDataSet` error and
include test to check this error is correctly returned from the
transform package.
Co-authored-by: Rahul Patel <rahulpa@google.com>
