microsoft-azure-storage/src/com/microsoft/azure/storage/core/Utility.java
public static String getUTCTimeOrEmpty(final Date value) {
        if (value == null) {
            return Constants.EMPTY_STRING;
        }

        final DateFormat iso8601Format = new SimpleDateFormat(ISO8601_PATTERN, LOCALE_US);
        iso8601Format.setTimeZone(UTC_ZONE);

        return iso8601Format.format(value);
    }
public static String getUTCTimeOrEmpty(final Date value) {
        if (value == null) {
            return Constants.EMPTY_STRING;
        }

        final DateFormat iso8601Format = new SimpleDateFormat(ISO8601_PATTERN, LOCALE_US);
        iso8601Format.setTimeZone(UTC_ZONE);

        return iso8601Format.format(value);
    }
Returns the UTC date/time for the specified value using the ISO8601 pattern.

@param value
A <code>Date</code> object that represents the date to convert to UTC date/time in the ISO8601
pattern. If this value is <code>null</code>, this method returns an empty string.

@return A <code>String</code> that represents the UTC date/time for the specified value using the ISO8601
pattern, or an empty string if <code>value</code> is <code>null</code>.