public String getIndexFieldBoost() {
                return "boost";
            }

            @Override
            public String getIndexFieldContentLength() {
                return "content_length";
            }

            @Override
            public String getIndexFieldHost() {
                return "host";
            }

            @Override

        if (fileTypeHelper != null) {
            // filetype
            putResultDataBody(dataMap, fessConfig.getIndexFieldFiletype(), fileTypeHelper.get(mimeType));
        }
        // content_length
        putResultDataBody(dataMap, fessConfig.getIndexFieldContentLength(), Long.toString(responseData.getContentLength()));
        // last_modified
        final Date lastModified = responseData.getLastModified();

  /** The HTTP {@code Cache-Control} header field name. */
  public static final String CACHE_CONTROL = "Cache-Control";

  /** The HTTP {@code Content-Length} header field name. */
  public static final String CONTENT_LENGTH = "Content-Length";

  /** The HTTP {@code Content-Type} header field name. */
  public static final String CONTENT_TYPE = "Content-Type";

  /** The HTTP {@code Date} header field name. */