Unable to make field private static final java.util.HashMap java.lang.ProcessEnvironment.theEnvironment accessible
The stack trace mentions "au.com.onegeek.sbtdotenv", so apparently this is coming from https://github.com/mefellows/sbt-dotenv.
You could try upgrading to the latest version of that plugin and see if the problem goes away.
If it doesn't, you could report the issue to the maintainer.
In that repo's README, there is a section about similar errors: https://github.com/mefellows/sbt-dotenv#illegal-reflective-access-warnings
It isn't clear to me if that's the same or different.