private String canonicalizeMetricName(String in) {
    return in.toLowerCase(Locale.ROOT).replaceAll("[^A-Za-z0-9 ]", "");
  }
A helper class that will allow tests to get into hadoop2's metrics2 values.
hbase-hadoop-compat/src/test/java/org/apache/hadoop/hbase/test/MetricsAssertHelperImpl.java