/**
  * Formats a header element.
  *
  * @param elem the header element to format
  * @param quote <code>true</code> to always format with quoted values, <code>false</code> to use
  *     quotes only when necessary
  * @param formatter the formatter to use, or <code>null</code> for the {@link #DEFAULT default}
  * @return the formatted header element
  */
 public static final String formatHeaderElement(
     final HeaderElement elem, boolean quote, HeaderValueFormatter formatter) {
   if (formatter == null) formatter = BasicHeaderValueFormatter.DEFAULT;
   return formatter.formatHeaderElement(null, elem, quote).toString();
 }