Go to Preferences/Java/Installed JREs/Properties
Modify Default VM arguments: after modifying the arguments they are not being taken into effect unless IDE is restarted.
I am observing this issue with all STS versions since 2015
I can't reproduce this with the latest STS 4.2.1 on macOS, so hard to tell what is going wrong here. Can you double check with a vanilla Eclipse 2019-03 install?
Go to Preferences/Java/Installed JREs/Properties Modify Default VM arguments: after modifying the arguments they are not being taken into effect unless IDE is restarted. I am observing this issue with all STS versions since 2015