RFR: 8368856: Add a method that performs saturating addition of a Duration to an Instant [v7]

[Roger Riggs]

On Thu, 9 Oct 2025 19:34:58 GMT, Pavel Rappo <prappo at openjdk.org> wrote:

>> As specified and implemented, `Duration.plus(long amount, TemporalUnit)` does not make an exception for amount == 0.  For any other value of month or years, the value is an estimate and the exception is thrown.
>> It might be useful to consider a change (as a separate enhancement)
>
>> As specified and implemented, `Duration.plus(long amount, TemporalUnit)` does not make an exception for amount == 0. For any other value of month or years, the value is an estimate and the exception is thrown. It might be useful to consider a change (as a separate enhancement)
> 
> I'm not sure that I completely understand what you are saying. Are you saying that a zero of any unit is still zero and, if added, could result in the initial instant rather than throw an exception if the unit is "incompatible" with `Instant`?
> 
> If so, then it reminds me of the following problem: should an unmodifiable set allow to delete an element which it does not contain? Different APIs decide differently. For example, this throws an exception:
> 
>     Set.of().remove(1)
> 
> Whereas this doesn't:
> 
>     Collections.emptySet().remove(1)
> 
> I don't know java.time deeply enough to lean one way or the other. But my gut feeling tells me that unconditional exception is easier to reason about and is more reliable.

It was a suggestion for a different issue/PR. 
It could allow a Period that has months == 0 and years = 0 but a days != 0 to be added.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/27549#discussion_r2433050354