code: public JSONReader perOperationInstance(int features, JsonParser p)
      {
          if (getClass() != JSONReader.class) { // sanity check
              throw new IllegalStateException("Sub-classes MUST override perOperationInstance(...)");
          }
          return new JSONReader(this, features,
                  _readerLocator.perOperationInstance(this, features), p);
      }
docs: /*
  ********************************************************************
  /* New instance creation
  ********************************************************************