public static String formatStandardDate(final Instant instant) {
        return formatDate(instant, FORMATTER_RFC1123);
    }
Formats the given instant according to the RFC 1123 pattern.

@param instant Instant to format.
@return An RFC 1123 formatted instant string.

@see #PATTERN_RFC1123

@since 5.2
httpclient5/src/main/java/org/apache/hc/client5/http/utils/DateUtils.java