Java – why does the time zone mode “oooo” not display the full GMT 00:00 offset format?

Is this an error or a function?

Datetimeformatter Javadoc clearly states that when I use oooo mode in the formatter, I should use the full form of localized time zone (emphasize my):

But if the time is 0 GMT:

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("EEE yyyy.MM.dd HH:mm:ss.SSS OOOO");

String timestamp = OffsetDateTime.ofInstant(Instant.Now(),ZoneOffset.UTC).format(formatter);
System.out.println(timestamp);

This is the output:

Mon 2019.02.25 22:30:00.586 GMT

expect:

Mon 2019.02.25 22:30:00.586 GMT+00:00