jshell tool: cannot handle non-ascii characters

FULL PRODUCT VERSION :
jdk9 ea b 136

ADDITIONAL OS VERSION INFORMATION :
Win 7 64 bit

A DESCRIPTION OF THE PROBLEM :
Try to enter a string with German umlauts at the jshell command prompt

"opü" will be "op?"
"üöä" will be "???"

jshell cannot handle these characters. Maybe this problem affects all non-ascii characters?

Using Linux I can not double-check this problem, because my terminal window cannot handle the umlauts too. A windows shell displays the German umlauts correctly,but the jshell started from there does not.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
see description

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
shell handles all non-ascii charecters correctly
ACTUAL -
jshell replaced German umlaut (maybe all non-ascii characters?) by a question mark

REPRODUCIBILITY :
This bug can be reproduced always.