docs: public static void main(String[] args) {
      System.out.println("Hello Stats World");
      System.out.println("Default Tags: " + tagger.empty());
      System.out.println("Current Tags: " + tagger.getCurrentTagContext());
      TagContext tags1 = tagger.emptyBuilder().put(K1, V1).put(K2, V2).build();
      try (Scope scopedTagCtx1 = tagger.withTagContext(tags1)) {
        System.out.println("  Current Tags: " + tagger.getCurrentTagContext());
        System.out.println(
            "  Current == Default + tags1: " + tagger.getCurrentTagContext().equals(tags1));
        TagContext tags2 = tagger.toBuilder(tags1).put(K3, V3).put(K4, V4).build();
        try (Scope scopedTagCtx2 = tagger.withTagContext(tags2)) {
          System.out.println("    Current Tags: " + tagger.getCurrentTagContext());
          System.out.println(
              "    Current == Default + tags1 + tags2: "
                  + tagger.getCurrentTagContext().equals(tags2));
          statsRecorder.newMeasureMap().put(M1, 0.2).put(M2, 0.4).record();
        }
      }
      System.out.println(
          "Current == Default: " + tagger.getCurrentTagContext().equals(tagger.empty()));
    }