RFR: 8332303: Better JMX interoperability with older JDKs, after removing Subject Delegation [v3]

[Daniel Fuchs]

On Thu, 16 May 2024 20:17:18 GMT, Kevin Walls <kevinw at openjdk.org> wrote:

>> Running JConsole from a previous JDK, and attaching to jdk-23 (after [JDK-8326666](https://bugs.openjdk.org/browse/JDK-8326666): Remove the Java Management Extension (JMX) Subject Delegation feature), the MBean tab is blank.
>> 
>> In javax/management/remote/rmi/RMIConnectionImpl.java:
>> addNotificationListener rejects a non-null delegationSubjects array, but older JDKs will send such an array. It could accept the array, and only reject/throw if it contains a non-null Subject (i.e. if an attempt to use subject delegation is really happening).
>> 
>> Manually testing JConsole, the MBean tab is fully populated and usable.
>
> Kevin Walls has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - add an 'also'
>  - typo

Marked as reviewed by dfuchs (Reviewer).

src/java.management.rmi/share/classes/javax/management/remote/rmi/RMIConnection.java line 979:

> 977:      * @throws IOException if a general communication exception occurred.
> 978:      * @throws UnsupportedOperationException if {@code delegationSubjects}
> 979:      * contains any non-null values.

Suggestion:

     * @throws UnsupportedOperationException if {@code delegationSubjects}
     * is non-null and contains any non-null values.

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PR Review: https://git.openjdk.org/jdk/pull/19253#pullrequestreview-2062912013
PR Review Comment: https://git.openjdk.org/jdk/pull/19253#discussion_r1604707244