* Add `sum` function in meter system

* Fix minor potential bug and reformat some codes

* Fix a bug

* Use Set to hold the {aggregate,scope} labels as same labels maybe added by multiple aggregation functions

* Separate downsampling function and revert unnecessary codes

Happy Chinese New Year !!

Support multiple implementations of StorageBuilder in different storage implementations - stage 2 (#6336)

Support multiple implementations of StorageBuilder in different storage implementations - stage 1. (#6334)

Add some defensive codes for NPE and bump up Kubernetes client version to expose exception stack trace (#6327)

* [maven-release-plugin] prepare release v8.4.0

* [maven-release-plugin] prepare for next development iteration

Fix that the dynamic configuration is deleted on the server side but does not take effect on the agent. (#6255)
Co-authored-by: 吴晟 Wu Sheng <wu.sheng@foxmail.com>

Fix bug that the same sample name in one MAL expression caused `IllegalArgumentException` in `Analyzer.analyse`. (#6250)