How to change Eclipse-Groovy plugin Groovy libraries? - eclipse

Question

I am using the newest version (2.8.0) of the Eclipse-Groovy plugin that ships with groovy-all-2.1.5.jar. I added Guice to my Groovy project, and when I go to run them from inside Eclipse I get the following error in the console output:
Caught: java.lang.NoClassDefFoundError: org/codehaus/groovy/runtime/typehandling/ShortTypeHandling
java.lang.NoClassDefFoundError: org/codehaus/groovy/runtime/typehandling/ShortTypeHandling
at net.me.myapp.utils.restclient.RestClient.<init>(RestClient.groovy:57)
at net.me.myapp.inject.UserServiceClientModule.configure(UserServiceClientModule.groovy:34)
at com.google.inject.AbstractModule.configure(AbstractModule.java:59)
at com.google.inject.spi.Elements$RecordingBinder.install(Elements.java:223)
at com.google.inject.spi.Elements.getElements(Elements.java:101)
at com.google.inject.internal.InjectorShell$Builder.build(InjectorShell.java:133)
at com.google.inject.internal.InternalInjectorCreator.build(InternalInjectorCreator.java:103)
at com.google.inject.Guice.createInjector(Guice.java:95)
at com.google.inject.Guice.createInjector(Guice.java:72)
at com.google.inject.Guice.createInjector(Guice.java:62)
at net.me.myapp.UserServiceClient.<init>(UserServiceClient.groovy:37)
at net.me.myapp.UserServiceClient.main(UserServiceClient.groovy:45)
Caused by: java.lang.ClassNotFoundException: org.codehaus.groovy.runtime.typehandling.ShortTypeHandling
... 12 more
According to this answer it's because ShortTypeHandling wasn't added until 2.3.x. So I would now like to attach groovy-all-2.3.3.jar to my Eclipse project's classpath.
The problem is that I don't seem to have edit permissions to change what library the Groovy Libraries library uses under the hood. And when I manually add the 2.3.3 JAR to my build path, I get the following error:
Caught: java.lang.ExceptionInInitializerError
java.lang.ExceptionInInitializerError
Caused by: groovy.lang.GroovyRuntimeException: Conflicting module versions. Module [groovy-all is loaded in version 2.1.5 and you are trying to load version 2.3.3
What are my options?

Answer 1

Groovy-eclipse versions have its own compilers and are "locked" to them. You may change the versions to whatever is listed under Window > Preferences > Groovy > Compilers, but, AFAIK, you can't change to an arbitrary version of the compiler by simply changing the groovy-all jar in the guts of the plugin dir.
You can install new compiler versions using the update site or eclipse marketplace
Update: install additional compiler versions through Help > Install new Software, select Groovy update site and expand the Extra Groovy Compilers session:
Note i'm using snapshot update site, because i like to live dangerously.