Remove setting of null security manager

[timja]

Running an agent on Java 17:

WARNING: A terminally deprecated method in java.lang.System has been called
WARNING: System::setSecurityManager has been called by hudson.remoting.jnlp.Main (file:/Users/timja/Downloads/agent.jar)
WARNING: Please consider reporting this to the maintainers of hudson.remoting.jnlp.Main
WARNING: System::setSecurityManager will be removed in a future release

[jglick]

All of these links are dead.

[oleg-nenashev]

Maybe not a chore, but whatever. Thanks for the patch!

[oleg-nenashev]

We may merge it in 24 hours if there is no negative feedback. Please see the merge process documentation for more information about the merge process

[timja]

@jeffret-b / @oleg-nenashev can we ship this?

[jeffret-b]

@timja , sure, that's fine.

[timja]

Could this be released @jeffret-b @oleg-nenashev ?

[AckermannC]

I think this change is causing an issue when trying to install the jenkins agent using java webstart.
See this issue: https://issues.jenkins.io/browse/JENKINS-67000

[MarkEWaite]

I think this change is causing an issue when trying to install the jenkins agent using java webstart. See this issue: https://issues.jenkins.io/browse/JENKINS-67000

Based on https://stackoverflow.com/questions/19487407/impact-of-system-setsecuritymanagernull, I think that this was the right change to make. Disabling applet security checks seems like a very risky choice.

[AckermannC]

I think this change is causing an issue when trying to install the jenkins agent using java webstart. See this issue: https://issues.jenkins.io/browse/JENKINS-67000

Based on https://stackoverflow.com/questions/19487407/impact-of-system-setsecuritymanagernull, I think that this was the right change to make. Disabling applet security checks seems like a very risky choice.

I get it, security is important to you and you don't think time should be wasted on fixing old technology... You are very outspoken on this in case 67000.
But there is still the launch-button offered in jenkins and in some environments it makes the work much easier.
If there is a more secure way to fix this great. It just would be nice if this would be implemented in the next version,