Parameterize KeyValue in AnnotationHandler #6786
Description
AnnotationHandler lets you customize the type where you set the metadata (type T) but it does not let you customize the metadata type itself. It is hard-coded KeyValue instead of a type parameter which causes issues (see: #6667 (comment)) and also KeyValue is used at places where it is not needed (CountedMeterTagAnnotationHandler and MeterTagAnnotationHandler both need to use KeyValue while they need to set Tag).
Doing this is a breaking change so probably something we can consider for 2.x.