RFR: 8364182: Add jcmd VM.properties command [v6]

[Alan Bateman]

On Fri, 9 Jan 2026 18:38:53 GMT, Kieran Farrell <kfarrell at openjdk.org> wrote:

>> The goal of this PR is to add a means of exposing security properties at runtime to aid the debugging security related issues/misconfigurations etc. Currently, only initial security properties set at start up can be exposed via the `InitialSecurityProperty` JFR event. 
>> 
>> This patch introduces a new jcmd diagnostic command `VM.properties`, which enables developers to print either the current system properties or security properties of a running Java process via command-line arguments (-system or -security). To avoid clutter within the jcmd command list, the old `VM.system_properties` command is hidden, but not removed so will not break existing usages. The implementation of each is shared to reduce duplication.
>
> Kieran Farrell has updated the pull request incrementally with one additional commit since the last revision:
> 
>   sperate VM.sec_props command

I think the latest proposal with `jcmd VM.security_properties` looks reasonable. My guess is that many developers don't know about security properties, or might think they are system properties that do something magic with security. So I think expand the current help/description from "Print security properties" to include "java.security.Security" in the text so there is somewhere to go and learn what this is.

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PR Comment: https://git.openjdk.org/jdk/pull/29124#issuecomment-3749232175