A DESCRIPTION OF THE PROBLEM :
A string with a leading combining diacritic (https://en.wikipedia.org/wiki/Combining_Diacritical_Marks) will render improperly in jshell

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Open a new jshell instance and create a string with a leading combining diacritic

jshell> "\u032Ea"

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
jshell should visually separate the double-quotation mark from the string's actual contents

$1 ==> "‌̮a"

This can be done either by unconditionally emitting a zero-width, non-joiner (\u200C) or by detecting the presence of a leading combining diacritic in a string and conditionally emitting the zero-width, non-joiner.
ACTUAL -
The diacritic has combined with jshell's double-quote mark.

$1 ==> "̮a"

FREQUENCY : always