public static Metrics create(Map<String,String> dimensionMap){
  Map<String,String> map=Maps.newTreeMap();
  map.putAll(dimensionMap);
  return new Metrics(Collections.unmodifiableMap(map));
}

public static Metrics create ( Map < String , String > dimensionMap ) { Map < String , String > map = Maps . newTreeMap ( ) ; map . putAll ( dimensionMap ) ; return new Metrics ( Collections . unmodifiableMap ( map ) ) ; }
creates a metrics object with the dimensions map immutable
