code: @Override
    public DefaultJsonWriter nullValue() {
      if (deferredUnescapeName != null || deferredName != null) {
        if (serializeNulls) {
          writeDeferredName();
        } else {
          deferredUnescapeName = null;
          deferredName = null;
          return this; // skip the name and the value
        }
      }
      beforeValue(false);
      out.append("null");
      return this;
    }
docs: {@inheritDoc}