RFR: 8326666: Remove the Java Management Extension (JMX) Subject Delegation feature

[Kevin Walls]

On Tue, 27 Feb 2024 10:44:20 GMT, Kevin Walls <kevinw at openjdk.org> wrote:

> The deprecated Subject Delegation feature in JMX will be removed.
> 
> This was marked in JDK 21 as deprecated for removal (JDK-8298966).

This covers the public interface to the feature, and tests.

Locally the feature is refused during a call to getMBeanServerConnection(with a non-null delegationSubject).

Remotely, `javax.management.remote.rmi.RMIConnectionImpl` has methods which accept a Subject parameter for Subject Delegation.  This cannot now be non-null in local usage, but an RMI Connection from an older JDK can invoke these methods with a non-null delegationSubject.  Such access will be recognised and an UnsupportedOperationException will be thrown (which the client will see).

RMIConnectionImpl can be simplified, and the class SubjectDelegator removed.

JMXSubjectDomainCombiner I would like to remove separately after this is done.

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PR Comment: https://git.openjdk.org/jdk/pull/18025#issuecomment-1972845693