The ISO time formatter that formats or parses a time without an offset, such as '10:15' or '10:15:30'.

This returns an immutable formatter capable of formatting and parsing the ISO-8601 extended local time format. The format consists of:

Two digits for the hour-of-day. This is pre-padded by zero to ensure two digits.
A colon
Two digits for the minute-of-hour. This is pre-padded by zero to ensure two digits.
If the second-of-minute is not available then the format is complete.
A colon
Two digits for the second-of-minute. This is pre-padded by zero to ensure two digits.
If the nano-of-second is zero or not available then the format is complete.
A decimal point
One to nine digits for the nano-of-second. As many digits will be output as required.

The returned formatter has no override chronology or zone. It uses the STRICT resolver style.