RFR: JDK-8285497: Add system property for Java SE specification maintenance version [v5]

[Mark Reinhold]

On Fri, 29 Apr 2022 02:12:19 GMT, Iris Clark <iris at openjdk.org> wrote:

>> Joe Darcy has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Change punctuation from review feedback.
>
> src/java.base/share/classes/java/lang/System.java line 743:
> 
>> 741:      *         have the value {@code "1"}; after a second maintenance
>> 742:      *         release, this property will have the value {@code "2"},
>> 743:      *         and so on.
> 
> There should be no requirement that values be allocated sequentially.  In other words, if JCP MR <x> does not require an RI, then it should not be surprising if there is no JDK build with maintenance version <x>.  As an example, JSR 337 MR 1 and MR 2 both used the same RI.  If this system property had existed during development of MR 1, it would return "1".  Since no RI was submitted for MR 2, a build returning "2" should never exist.  MR 3 did update the RI, so it would return "3".

@irisclark does raise an interesting point: If, say, MR 2 doesn’t require a change to the RI then the MR 1 RI is also the MR 2 RI, but its `java.specification.maintenance.version` property will report that it’s the MR 1 RI.

One way to fix this would be to require an RI update with every MR just to update this property, even if no other code in the RI changes — but we prefer to avoid doing RI builds unnecessarily.

Another way to fix it would be to finesse the specification of this property, perhaps:


     * <tr><th scope="row">{@systemProperty java.specification.maintenance.version}</th>
     *     <td>Java Runtime Environment specification maintenance version, which may
     *         be interpreted as a non-zero integer. If defined, the value of this
     *         property is the identifying number of the most recent <a
     *         href="https://jcp.org/en/procedures/jcp2#3.6.4">specification
     *         maintenance release</a> that required a change to the runtime</a>
     *         <em>(optional)</em>.
     *         </td></tr>

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PR: https://git.openjdk.java.net/jdk/pull/8437