This commit introduces a notion of different styles for the formatting
of Duration.
The `@DurationFormat` annotation is added to ease selection of a style,
which are represented as DurationFormat.Style enum, as well as a
supported time unit represented as DurationFormat.Unit enum.
DurationFormatter has been retroffited to take such a Style,
optionally, at construction. The default is still the JDK style a.k.a.
ISO-8601.
This introduces the new SIMPLE style which uses a single number + a
short human-readable suffix. For instance "-3ms" or "2h".
This has the same semantics as the DurationStyle in Spring Boot and
is intended as a replacement for that feature, providing access to the
feature to projects that only depend on Spring Framework.
Finally, the `@Scheduled` annotation is improved by adding detection
of the style and parsing for the String versions of initial delay, fixed
delay and fixed rate.
See gh-22013
See gh-22474
Closes gh-30396
c92e043bbc