Custom resources
CRDs are in widespread use as a Kubernetes extensibility mechanism and have been available in beta since the 1.7 release. The 1.16 release marks the graduation of CRDs to general availability (GA).
Overhauled metrics
Kubernetes has previously made extensive use of a global metrics registry to register metrics to be exposed. By implementing a metrics registry, metrics are registered in more transparent means. Previously, Kubernetes metrics have been excluded from any kind of stability requirements.