support openmetrics symbolic views

nb-api/src/main/java/io/nosqlbench/api/labels/MapLabels.java

@@ -120,6 +120,18 @@ public class MapLabels implements NBLabels {
         return sb.toString();
     }
 
+    @Override
+    public String linearizeAsMetrics() {
+        StringBuilder sb = new StringBuilder("{");
+        this.labels.forEach((k,v) -> {
+            sb.append(k).append(":\"").append(v).append("\",");
+        });
+        sb.setLength(sb.length()-",".length());
+        sb.append("}");
+        return sb.toString();
+
+    }
+
     @Override
     public MapLabels and(final Object... labelsAndValues) {
         final Map<String,String> childLabels = getStringStringMap(labelsAndValues);

nb-api/src/main/java/io/nosqlbench/api/labels/NBLabels.java

@@ -170,6 +170,8 @@ public interface NBLabels {
      */
     Map<String, String> asMap();
 
+    String linearizeAsMetrics();
+
     /**
      * @return a new set of labels which includes only those which are not using per-instance semantics.
      */