code: private String buildString() {
      if (type.isSimpleType()) {
        return '"' + type.name().toLowerCase() + '"';
      }
      StringBuilder builder = new StringBuilder();
      JsonWriter writer = new JsonWriter(CharStreams.asWriter(builder));
      try {
        new SchemaTypeAdapter().write(writer, this);
        writer.close();
        return builder.toString();
      } catch (IOException e) {
        // It should never throw IOException on the StringBuilder Writer, if it does, something very wrong.
        throw Throwables.propagate(e);
      }
    }
docs: Helper method to encode this schema into json string.
  
  @return A json string representing this schema.