code: public <T> T parseAs(Class<T> dataClass) throws IOException {
      if (!hasMessageBody()) {
        return null;
      }
      return request.getParser().parseAndClose(getContent(), getContentCharset(), dataClass);
    }
docs: Parses the content of the HTTP response from {@link #getContent()} and reads it into a data
  class of key/value pairs using the parser returned by {@link HttpRequest#getParser()}.
  
  <p><b>Reference:</b> http://tools.ietf.org/html/rfc2616#section-4.3
  
  @return parsed data class or {@code null} for no content