system encoding used by java command line argument files instead of UTF-8

A DESCRIPTION OF THE PROBLEM :
https://openjdk.java.net/jeps/400 was seen as promise that only UTF-8 would be needed anymore,
but we just see the definition that java command argument files still use system encoding.
see https://docs.oracle.com/en/java/javase/18/docs/specs/man/java.html#java-command-line-argument-files
"characters in system default encoding"

In eclipse IDE we have the issue https://github.com/eclipse-jdt/eclipse.jdt.debug/issues/45 that the IDE supports both Java 11 and 18 which does not provide any consistent method to get the system encoding (was Charset#defaultCharset)