Official JAVA 17 (LTS) support

[HoneyBadgerSeeker]

Is your feature request related to a problem? Please describe.
No, not for now, it seems working fine with Java 17.

Describe the solution you'd like
The new LTS version of Java is available (Java 17).
FitNesse should be officially compatible with it.

The FitNesse download page, state that

Ensure you have a supported Java version installed (either version 8 or 11, versions >= 15 are not supported).

[enexusde]

Using RestFixtures a

Could not complete testing: java.lang.UnsupportedOperationException: The Security Manager is deprecated and will be removed in a future release

Exception is thrown.

[fhoeben]

@enexusde is the exception thrown from RestFixture code (if so you should probably file the issue at https://github.com/smartrics/RestFixture), or from FitNesse itself?

If the error comes from FitNesse, can you provide a stack trace where the exception is thrown and preferably a reproduction path using the only code present in this project?

[tcnh]

I've seen that same exception, but only with a Java 18 JRE. That's where it was removed from the runtime.

[enexusde]

@fhoeben From FitNesse

[lehtmets]

I saw this waring with Java 17 (17.0.6 temurin)
WARNING: A terminally deprecated method in java.lang.System has been called
WARNING: System::setSecurityManager has been called by fitnesse.slim.instructions.SystemExitSecurityManager (file:/Users/ml/.gradle/caches/modules-2/files-2.1/org.fitnesse/fitnesse/20221102/b5ce9b528912742591c26c6893e8e091aeed543a/fitnesse-20221102.jar)
WARNING: Please consider reporting this to the maintainers of fitnesse.slim.instructions.SystemExitSecurityManager
WARNING: System::setSecurityManager will be removed in a future release