src/main/java/org/efaps/ui/wicket/components/date/DateTimePanel.java
protected boolean use12HourFormat()
    {
        final String pattern = DateTimeFormat.patternForStyle("-S", getLocale());
        return pattern.indexOf('a') != -1 || pattern.indexOf('h') != -1 || pattern.indexOf('K') != -1;
    }
protected boolean use12HourFormat()
    {
        final String pattern = DateTimeFormat.patternForStyle("-S", getLocale());
        return pattern.indexOf('a') != -1 || pattern.indexOf('h') != -1 || pattern.indexOf('K') != -1;
    }
Depending on the locale am/pm is used or not.

@return true if 12 hour format else false