A MetricRegistry can have a metric prefix strategy.  Also, ConsoleAppend...

...er synchronizes over the output stream to ensure thread-safe appending.

My use case includes many client tenants in each JVM, and there are a few per-client metrics we'd like to expose, but don't want to modify the metric annotations currently in place.  This allows the MetricRegistry to prepend a metric prefix for metrics in play.

remove() may be suspicious.  I guess it depends on what you think of the feature itself as to what "correct" looks like.