* Update License header for all source files
- Add Apache 2.0 header to source files that did not have one.
- Update all existing headers dated to 2019 to be 2020
- Remove comma from License header to comply with the Apache 2.0
guidelines.
* Update Copyright notice
Use the standard Copyright notices outlined by the
[CNCF](https://github.com/cncf/foundation/blob/master/copyright-notices.md#copyright-notices)
* copy of simplelru for attributes without excessive usage of interface{}
This also make sure we only add attributes/links if isRecording.
Move method to export the attributes list to attributeMap.
* run make precommit to update mod files.