Fails to compile: dependencies out of date

[bethcodes]

This won't compile with the current version of maven/Java because the version of maven is too far out of date. If I update the dependencies in the pom.xml, I get an error from the (apparently-now-unsupported?) proguard-maven-plugin:
Failed to execute goal com.github.wvengen:proguard-maven-plugin:2.0.14:proguard (default) on project emitter: Obfuscation failed (result=1)

[kelindar]

@bethcodes coould you submit a PR with a fix?

[pengcheng789]

How to resolve the problem?