ADDITIONAL SYSTEM INFORMATION :
Microsoft Windows [Version 6.1.7601] x64

A DESCRIPTION OF THE PROBLEM :
Entering a classpath in jshell /env with a blank breaks after the first blank even in quotation marks

REGRESSION : Last worked in version 12.0.1

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
in jshell> enter
/env -class-path C:\Program Files\Java\javafx-sdk-12.0.1\lib\javafx.base.jar or
/env -class-path "C:\Program Files\Java\javafx-sdk-12.0.1\lib\javafx.base.jar" or
/env -class-path 'C:\Program Files\Java\javafx-sdk-12.0.1\lib\javafx.base.jar'

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Setting new options and restoring state.
ACTUAL -
| File '"C:\Program' for '--class-path' is not found.

CUSTOMER SUBMITTED WORKAROUND :
Copy the files to a path without blanks, e. g.

/env -class-path D:\javafx_12_lib\javafx.base.jar works !

FREQUENCY : always