docs: public void transform(JSONObject root) {
          Object[] keySet = root.keySet().toArray();
          for(Object k : keySet) {
              if (cond.check(k.toString())) {
                  this.transformer.transform(root, k); 
              }
              
              // apply recursively
              if (cond.isRecursive()) {
                  this.transform(root, k);
              }
          }
      }