FULL PRODUCT VERSION :
openjdk version "15-ea" 2020-09-15
OpenJDK Runtime Environment (build 15-ea+19-827)
OpenJDK 64-Bit Server VM (build 15-ea+19-827, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Windows Server 2016 Japanese

A DESCRIPTION OF THE PROBLEM :
Under non-UTF8 environment, such as Windows Japanese or Chinese,
"--describe-module" option with non-ASCII module name cannot find the module.

In the example below, we used "Hiragana letter A", U+3042, in the module name.

This is separated from javac's issue JDK-8233829.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Source codes are below.
1. > javac -d . test.java module-info.java
2. > java --module-path . --describe-module あ_module

EXPECTED VERSUS ACTUAL BEHAVIOR :
Expected:
>java --module-path . --describe-module あ_module
あ_module file:///C:/module/src/./
exports com.test
requires java.base mandated

Actual:
>java --module-path . --describe-module あ_module
??_modu not found (in Japanese)


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
--- module-info.java ---
module あ_module {
    exports com.test;
}
------------------------
--- test.java ---
package com.test;

public class test{
    public static void main(String[] args) {
        System.out.println("hello");
    }
}
-----------------

---------- END SOURCE ---------- 

Additional Information:
--list-modules option can list correctly.
> java.exe --list-modules -p .
(snip)
jdk.unsupported@15-ea
jdk.unsupported.desktop@15-ea
jdk.xml.dom@15-ea
jdk.zipfs@15-ea
あ_module file:///C:/module/src/./