A DESCRIPTION OF THE PROBLEM :
According to ISO_LOCAL_DATE's JavaDoc:
This returns an immutable formatter capable of formatting and parsing
     * the ISO-8601 extended local date format.
     * The format consists of:
     * <ul>
     * <li>Four digits or more for the {@link ChronoField#YEAR year}.
     * Years in the range 0000 to 9999 will be pre-padded by zero to ensure four digits.
     * Years outside that range will have a prefixed positive or negative symbol.
     * <li>A dash
     * <li>Two digits for the {@link ChronoField#MONTH_OF_YEAR month-of-year}.
     * This is pre-padded by zero to ensure two digits.
     * <li>A dash
     * <li>Two digits for the {@link ChronoField#DAY_OF_MONTH day-of-month}.
     * This is pre-padded by zero to ensure two digits.

The separator which splits years from months and months from days is the *hyphen-minus* (U+0x002D), ASCII's ambiguous character which is the only one resembling minuses, hyphens and dashes, not an actual dash, so calling it a dash is at least misleading.

Other DateTimeFormatter date formats (ISO_ORDINAL_DATE and ISO_WEEK_DATE) must have the same issue.

ISO 8601 uses hyphens as separators, so actually returning dashes would not comply. On the other hand, the hyphen-minus is the CSS hyphenate-character, so just changing the documentation will leave the issue that web pages consider such dates as containing line breaking opportunities, causing dates at the end of a line to be split on 2 lines. One solution might be to use the NON-BREAKING HYPHEN (U+0x2011).

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
ImHex can be used to open DateTimeFormatter.java and validate the issue, which can be found at line 801 (among others).


FREQUENCY : always