code: public static String encodeCookie(Cookie cookie) {
          int maxAge = -1;
          if (cookie.getExpiryDate() != null) {
              maxAge = (int) ((cookie.getExpiryDate().getTime() - System.currentTimeMillis()) / ONE_SECOND);
              // According to Cookie class specification, a negative value
              // would be considered as no value. That is not what we want!
              if (maxAge < 0) {
                  maxAge = 0;
              }
          }
  
          String cookieName = cookie.getName();
          String cookieValue = cookie.getValue();
  
          StringBuilder buffer = new StringBuilder();
  
          // Copied from org.apache.http.impl.cookie.BrowserCompatSpec.formatCookies(List<Cookie>)
          if (cookie.getVersion() > 0 && !isQuoteEnclosed(cookieValue)) {
              buffer.append(BasicHeaderValueFormatter.INSTANCE.formatHeaderElement(null,
                      new BasicHeaderElement(cookieName, cookieValue), false).toString());
          } else {
              // Netscape style cookies do not support quoted values
              buffer.append(cookieName);
              buffer.append("=");
              if (cookieValue != null) {
                  buffer.append(cookieValue);
              }
          }
          // End copy
  
          appendAttribute(buffer, "Comment", cookie.getComment());
          appendAttribute(buffer, "Domain", cookie.getDomain());
          appendAttribute(buffer, "Max-Age", maxAge);
          appendAttribute(buffer, "Path", cookie.getPath());
          if (cookie.isSecure()) {
              appendAttribute(buffer, "Secure");
          }
          if (((BasicClientCookie) cookie).containsAttribute(HTTP_ONLY_ATTR)) {
              appendAttribute(buffer, "HttpOnly");
          }
          appendAttribute(buffer, "Version", cookie.getVersion());
  
          return (buffer.toString());
      }
docs: Utility method to transform a Cookie into a Set-Cookie Header.
  
  @param cookie
  the {@link Cookie} to format
  
  @return the value of the Set-Cookie header