In JMC 6.0.0, bundled with JDK 9,
we have changed the default behavior when setting vmargs for JMC.

The options should change from:

-vmargs <jvm-arguments>
Override the jvm arguments specified in the jmc.ini file located in JDK/bin

--launcher.appendVmargs
Append jvm arguments to the -vmargs flag to those in the jmc.ini file.



to:

-vmargs <jvm-arguments>
Append <jvm-arguments> to the the jvm arguments specified in the jmc.ini file located in JDK/bin

--launcher.overrideVmargs
Override the jvm arguments from the jmc.ini file with those specified with the -vmargs flag.