[Joda-interest] ISODateTimeFormat thread safety

[Lin W. <sup...@gm...>]

The javadoc of ISODateTimeFormat class says it's thread-safe and immutable.
The static fields are lazily initialized. However it seems it's not done in
a thread-safe manner.

For example, dt is lazily initialized in
    public static DateTimeFormatter dateTime() {
        if (dt == null) {
            dt = new DateTimeFormatterBuilder()
                .append(date())
                .append(tTime())
                .toFormatter();
        }
        return dt;
    }

When there are two threads both inside this method, is it possible that one
thread sees an unsafely published non-null dt value due to cache
incoherence?

Did I miss something?