public static MetricsTag tag(MetricsInfo info, String value) {
    Map<String, MetricsTag> map = tagCache.getUnchecked(info);
    MetricsTag tag = map.get(value);
    if (tag == null) {
      tag = new MetricsTag(info, value);
      map.put(value, tag);
    }
    return tag;
  }
Get a metrics tag
@param info  of the tag
@param value of the tag
@return an interned metrics tag
hbase-hadoop-compat/src/main/java/org/apache/hadoop/hbase/metrics/Interns.java