code: protected Reader _createReader(InputStream in, JsonEncoding enc, IOContext ctxt) throws IOException
      {
          if (enc == null) {
              enc = JsonEncoding.UTF8;
          }
          // default to UTF-8 if encoding missing
          if (enc == JsonEncoding.UTF8) {
              boolean autoClose = ctxt.isResourceManaged() || isEnabled(JsonParser.Feature.AUTO_CLOSE_SOURCE);
              return new UTF8Reader(in, autoClose);
          }
          return new InputStreamReader(in, enc.getJavaName());
      }
docs: /*
  ********************************************************
  /* Internal methods
  ********************************************************