docs: @SuppressWarnings("unchecked")
    public Query withContentType(String contentType) {
      checkNotEmpty(contentType, "ContentType must not be empty.");
  
      if (hasContentTypeSet()) {
        throw new IllegalStateException(
            format("ContentType \"%s\" is already present in query.", contentType)
        );
      } else {
        params.put(PARAMETER_CONTENT_TYPE, contentType);
      }
  
      return (Query) this;
    }