RFR: 8215156: Deprecate the -Xfuture option

[Henry Jen]

Hi,

Please review a webrev[1] to deprecate the -Xfuture option per CSR-8224524[2].

Cheers,
Henry
 
[1] https://cr.openjdk.java.net/~henryjen/jdk13/8215156/open/webrev/
[2] https://bugs.openjdk.java.net/browse/JDK-8224524