Adjusting Polyglot Sampler to GR-54300

[JaroslavTulach]

• There is a problem initializing VisualVM 2.2 Polyglot Sampler with Truffle 25.0.0 when the application is running in module path mode.
• this is caused by GR-54300 changes that modified the ENGINES field from Map to Set which remained unnoticed for a while

Reproduce

• I've created a sample project https://github.com/jtulach/graaljs/tree/GraalJsDemo
• when executed in module path mode: mvn -Pmodulepath package exec:exec the VisualVM Polyglot Sampler can't connect
  • everything works in classpath mode
  • everything also works when one --add-opens access for the access to findActiveEngines method...

Fix

This change modifies the Unsafe code of the stagent to be ready for Map as well as Set value being returned from the field.

CCing @tzezula

[thurka]

Could you please file it as a bug? Thanks.

[JaroslavTulach]

Could you please file it as a bug? Thanks.

• Cannot initialize Polygot Sampler in --module-path mode #657 has just been reported